- --------------------------------------------------------------------------------
                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                             -----------------------

                                    FORM 10-Q


                QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(D)
                     OF THE SECURITIES EXCHANGE ACT OF 1934
                             -----------------------

                  FOR THE QUARTERLY PERIOD ENDED MARCH 31, 2003

                        COMMISSION FILE NUMBER 000-21930


                          BIOSOURCE INTERNATIONAL, INC.
             (Exact name of Registrant as specified in its charter)

            DELAWARE                                            77-0340829
(State or other jurisdiction of                             (I.R.S. Employer
  incorporation or organization)                             Identification No.)


                   542 FLYNN ROAD, CAMARILLO, CALIFORNIA 93012
               (Address of principal executive offices) (Zip Code)


       Registrant's telephone number, including area code: (805) 987-0086


     Indicate  by check mark  whether the  Registrant  (1) has filed all reports
required to be filed by Section 13 or 15(d) of the  Securities  Exchange  Act of
1934  during the  preceding  12 months  (or for such  shorter  periods  that the
Registrant was required to file such reports),  and (2) has been subject to such
filing requirements for the past 90 days.


                                YES [X]       NO [_]


     Indicate by check mark whether the registrant is an  accelerated  filer (as
defined in Rule 12b-2 of the Act). Yes [_] No [X].

The  number  of shares  of the  Registrant's  common  stock,  $.001  par  value,
outstanding as of May 9, 2003 was 9,553,705.


- --------------------------------------------------------------------------------





                 BIOSOURCE INTERNATIONAL, INC. AND SUBSIDIARIES
                                    FORM 10-Q
                                 MARCH 31, 2003

                                      INDEX


                                                                        PAGE NO.
                                                                        --------
                          PART I. FINANCIAL INFORMATION

ITEM 1.  UNAUDITED FINANCIAL STATEMENTS

            Condensed Consolidated Balance Sheets as of
            March 31, 2003 and December 31, 2002                             3

            Condensed Consolidated Statements of Operations
            for the three months ended March 31, 2003 and 2002               4

            Condensed Consolidated Statements of Cash Flows
            for the three months ended March 31, 2003 and 2002               5

            Notes to Condensed Consolidated Financial Statements             6

ITEM 2.  MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL
         CONDITION AND RESULTS OF OPERATIONS                                10

ITEM 3.  QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET
         RISK                                                               25

ITEM 4.  CONTROLS AND PROCEDURES                                            25


                           PART II. OTHER INFORMATION

ITEM 1.  LEGAL PROCEEDINGS                                                  27

ITEM 2.  CHANGES IN SECURITIES AND USE OF PROCEEDS                          27

ITEM 3.  DEFAULTS UPON SENIOR SECURITIES                                    27

ITEM 4.  SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS                27

ITEM 5.  OTHER INFORMATION                                                  27

ITEM 6.  EXHIBITS AND REPORTS ON FORM 8-K                                   27

SIGNATURES                                                                  28


                                       2





                 BIOSOURCE INTERNATIONAL, INC. AND SUBSIDIARIES
                      CONDENSED CONSOLIDATED BALANCE SHEETS
                             (Amounts in thousands)
                                   (Unaudited)


                                                        MARCH 31,   DECEMBER 31,
                                                          2003           2002
                                                        --------       --------

            ASSETS
Current assets:
   Cash and cash equivalents .....................      $  3,840          5,941
   Accounts receivable, less allowance
     for doubtful accounts of $264 at
     March 31, 2003 and $261 at
     December 31, 2002 ...........................         7,129          6,157
   Inventories, net (note 3) .....................         9,483          8,880
   Prepaid expenses and other current
     assets ......................................           862            538
   Deferred income taxes .........................         1,873          1,873
                                                        --------       --------
            Total current assets .................        23,187         23,389

Property and equipment, net (note 4) .............         7,186          7,398
Intangible assets net of accumulated
   amortization of $2,646 at March 31,
   2003 and $2,502 at December 31, 2002
   (note 5) ......................................         5,931          6,076
Goodwill .........................................           307            307
Other assets .....................................           537            526
Deferred tax assets ..............................         8,810          8,810
                                                        --------       --------
                                                        $ 45,958         46,506
                                                        ========       ========
            LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities:
   Accounts payable ..............................      $  2,639          3,115
   Accrued expenses ..............................         2,792          2,910
   Deferred revenue ..............................           378            427
   Income tax payable ............................           664            341
                                                        --------       --------
            Total current liabilities ............         6,473          6,793
                                                        --------       --------
Commitments and contingencies

Stockholders' equity:
   Common stock, $.001 par value
     Authorized 20,000,000 shares:
     issued and outstanding 9,610,305
     shares at March 31, 2003 and
     9,676,931 at December 31, 2002 ..............            10             10
  Additional paid-in capital .....................        43,929         44,500
  Accumulated deficit ............................        (3,279)        (3,382)
  Accumulated other comprehensive loss ...........        (1,175)        (1,415)
                                                        --------       --------
            Net stockholders' equity .............        39,485         39,713
                                                        --------       --------
                                                        $ 45,958         46,506
                                                        ========       ========


The  accompanying  notes are an integral  part of these  condensed  consolidated
financial statements.


                                       3





                 BIOSOURCE INTERNATIONAL, INC. AND SUBSIDIARIES
                 CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS
                   THREE MONTHS ENDED MARCH 31, 2003 AND 2002
                 (Amounts in thousands, except per share data)
                                   (Unaudited)


                                                         2003            2002
                                                       --------        --------

Net sales ......................................       $ 10,899           9,781
Cost of sales ..................................          4,690           4,196
                                                       --------        --------
    Gross profit ...............................          6,209           5,585
                                                       --------        --------

Operating expenses:
    Research and development ...................          1,979           1,293
    Sales and marketing ........................          2,388           2,266
    General and administrative .................          1,576           1,460
    Amortization of intangibles ................            145             160
                                                       --------        --------
         Total operating expenses ..............          6,088           5,179
                                                       --------        --------
Operating income ...............................            121             406

Interest income ................................             11              40
Other income (expense), net ....................            (18)             30
                                                       --------        --------
Income before income taxes .....................            114             476
Income tax expense .............................             11             105
                                                       --------        --------
         Income before cumulative effect
           of accounting change ................            103             371

Cumulative effect of accounting change
    (net of applicable income taxes $1,759) ....           --            (2,870)
                                                       --------        --------

Net income (loss) ..............................       $    103          (2,499)
                                                       ========        ========

Net income per share before accounting
change:
    Basic ......................................       $   0.01            0.04
                                                       ========        ========
    Diluted ....................................       $   0.01            0.03
                                                       ========        ========

Net income (loss) per share:
    Basic ......................................       $   0.01           (0.25)
                                                       ========        ========
    Diluted ....................................       $   0.01           (0.23)
                                                       ========        ========

Shares used to compute per share amounts:
    Basic ......................................          9,635          10,190
                                                       ========        ========
    Diluted ....................................         10,026          10,757
                                                       ========        ========



The  accompanying  notes are an integral  part of these  condensed  consolidated
financial statements.


                                       4





                 BIOSOURCE INTERNATIONAL, INC. AND SUBSIDIARIES
                 CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS
                   THREE MONTHS ENDED MARCH 31, 2003 AND 2002
                             (Amounts in thousands)
                                   (Unaudited)


                                                          2003            2002
                                                        -------         -------

Cash flows from operating activities:
    Net income (loss) ..........................        $   103          (2,499)
    Adjustments to reconcile net income
      (loss) to net cash provided by
      operating activities:
         Depreciation and amortization .........            653             496
         Cumulative effect of accounting
           change ..............................           --             4,629
         Income tax benefit from the
           exercise of stock options ...........           --                95
    Changes in assets and liabilities:
         Accounts receivable ...................           (864)           (379)
         Inventories ...........................           (350)           (162)
         Prepaid expenses and other
           current assets ......................           (324)             16
         Deferred income taxes .................           --            (1,759)
         Other assets ..........................            (11)            (69)
         Accounts payable ......................           (525)            436
         Accrued expenses ......................           (173)           (306)
         Deferred revenue ......................            (49)            (33)
         Income taxes payable ..................            313               9
                                                        -------         -------
    Net cash provided from (used in)
      operating activities .....................         (1,227)            569
                                                        -------         -------
Cash flows from investing activities:
    Purchase of property and equipment .........           (238)           (623)
                                                        -------         -------
         Net cash used in investing
           activities ..........................           (238)           (623)
                                                        -------         -------
Cash flows from financing activities:
    Proceeds from the exercise of options ......             95              40
    Payments to acquire treasury stock .........           (666)         (3,080)
                                                        -------         -------
    Net cash used in financing activities ......           (571)         (3,040)
                                                        -------         -------
         Net decrease in cash and cash
           equivalents .........................         (2,036)         (3,189)
Effect of exchange rates on cash and cash
  equivalents ..................................            (65)             58

Cash and cash equivalents at beginning
  of period ....................................          5,941           9,471
                                                        -------         -------
Cash and cash equivalents at end of period .....        $ 3,840           6,340
                                                        =======         =======

Supplemental  disclosure of cash flow
  information:
Cash paid during the period for:
         Interest ..............................        $  --                 1
                                                        =======         =======
         Income taxes ..........................        $  --              --
                                                        =======         =======



The  accompanying  notes are an integral  part of these  condensed  consolidated
financial statements.


                                       5





BIOSOURCE INTERNATIONAL, INC. AND SUBSIDIARIES
NOTES TO CONDENSED CONSOLIDATED UNAUDITED FINANCIAL STATEMENTS

1.   BASIS OF PRESENTATION

The  accompanying  condensed  consolidated  financial  statements  of  BioSource
International,  Inc.  (the  "Company")  are  unaudited  and have  been  prepared
pursuant to the rules and regulations of the Securities and Exchange  Commission
regarding interim financial reporting.  Accordingly,  they do not include all of
the  information  and  footnotes  required  by  generally  accepted   accounting
principles for complete  financial  statements and should be read in conjunction
with the  consolidated  financial  statements and notes thereto  included in our
Annual Report on Form 10-K,  for the fiscal year ended December 31, 2002. In the
opinion  of  management,   the  accompanying  unaudited  condensed  consolidated
financial  statements  include all  adjustments  that are  necessary  for a fair
presentation.  The results of  operations  for the three  months ended March 31,
2003,  are not  necessarily  indicative  of results to be expected  for the full
fiscal year.

2.   GENERAL

The  Company  develops,  manufactures,  markets  and  distributes  products  and
services that are widely used in biomedical research.  Our products and services
enable  scientists to better  understand the  biochemistry,  immunology and cell
biology of the human body, aging and certain diseases such as cancer,  arthritis
and other inflammatory diseases,  AIDS and certain other infectious diseases. We
have a wide  variety of  products,  including  immunoassay  and ELISA test kits;
immunological reagents, including bioactive proteins (cytokines,  growth factors
and  adhesion  molecules),   oligonucleotides,  and  monoclonal  and  polyclonal
antibodies. We also manufacture and market custom oligonucleotides, peptides and
antibodies  to the  specifications  of our  customers.  We use  recombinant  DNA
technology to produce cytokines and other proteins.

In the quarter ended March 31, 2003, the Company  capitalized its annual catalog
production costs. In the past, the Company has expensed catalog production costs
as incurred, which was primarily in the first quarter of its fiscal year. During
2002, and after  production of the catalog,  the Company put substantial  effort
into  increasing  the  number  of  customers  in its  customer  database  and in
conjunction  with that, its dependence on its catalog to attract more customers.
As a result,  the Company  believes that their 2003 catalog is a direct response
advertisement  whose primary purpose is to elicit sales to customers who respond
specifically  to the catalog  resulting  in probable  future  economic  benefit.
Accordingly,  beginning  in  2003,  the  Company  is  capitalizing  its  catalog
production  costs and  expensing  them  evenly  throughout  the  fiscal  year in
accordance with the AICPA's Statement of Position 93-07. In the first quarter of
2002, the Company expensed  approximately  $359,000 of catalog costs compared to
$113,000  for the first  quarter of 2003.  The Company does not  anticipate  its
annual catalog costs to be materially different from 2002 to 2003.

RECENTLY ISSUED ACCOUNTING STANDARDS

In June 2001,  the FASB issued SFAS No. 143,  "Accounting  for Asset  Retirement
Obligations."  SFAS No. 143  addresses  financial  accounting  and reporting for
obligations associated with the retirement of tangible long-lived assets and the
associated  asset  retirement  costs. The adoption of SFAS No. 143 on January 1,
2003 did not have a  material  impact on the  Company's  financial  position  or
results of operations.

In July 2001, the Financial Accounting Standards Board ("FASB") issued Statement
of Financial  Accounting  Standards  ("FAS")  No.141,  "Accounting  For Business
Combinations,"  and FAS No. 142,  "Accounting For Goodwill and Other  Intangible
Assets." FAS No. 141 requires that the purchase method of accounting be used for
all business  combinations  initiated  after June 30, 2002. FAS No. 142 requires
that goodwill and intangible  assets with  indefinite  useful lives no longer be
amortized to earnings, but instead be reviewed for impairment in accordance with
FAS No.  142.  Effective  January  1, 2002,  the  Company's  goodwill  and other
intangible  assets are accounted  for under FAS No. 141 "Business  Combinations"
and FAS No. 142 "Goodwill and Other Intangible  Assets." In the first quarter of
2002, the Company  recognized a non-cash charge, net of applicable income taxes,
of  $2,870,000  representing  the  cumulative  effect of a change in  accounting
principle  resulting from the implementation of FAS 142. The charge included the
write  off  of  goodwill  related  to the  acquisitions  of  Quality  Controlled
Biochemicals  ("QCB") and Biofluids in December 1998.  The Company  continues to
carry certain identifiable


                                       6





intangible  assets  with  definite  useful  lives  on  its  balance  sheet.  The
amortization   associated  with  these   identifiable   intangible   assets  was
approximately  $145,000 and  $160,000 for the quarters  ended March 31, 2003 and
2002, respectively.

In December  2002,  the FASB issued SFAS No. 148,  "Accounting  for  Stock-Based
Compensation  - Transition  and  Disclosure - an amendment of FASB Statement No.
123."  SFAS  No.  148  amends  SFAS  No.  123,   "Accounting   for   Stock-Based
Compensation,"  to provide  alternative  methods of  transition  for a voluntary
change to the fair value based method of  accounting  for  stock-based  employee
compensation.  In addition,  SFAS No. 148 amends the disclosure  requirements of
SFAS No.  123 to  require  prominent  disclosures  in both  annual  and  interim
financial  statements  about the method of accounting for  stock-based  employee
compensation  and the  effect  of the  method  used  on  reported  results.  The
disclosure  requirements  apply to all  companies  for fiscal years ending after
December 15, 2002. The interim disclosure provisions are effective for financial
reports  containing  financial  statements for interim  periods  beginning after
December 15, 2002.  The adoption of SFAS No. 148 did not have a material  impact
on the Company's consolidated financial statements.

In  January  2003,  the  FASB  issued  FASB   Interpretation   ("FIN")  No.  45,
"Guarantor's  Accounting and Disclosure  Requirements for Guarantees,  Including
Indirect  Guarantees and  Indebtedness of Others." FIN No. 45 requires a company
to  recognize a  liability  for the  obligations  it has  undertaken  to issue a
guarantee.  This  liability  would be recorded at the inception of the guarantee
and  would  be  measured  at fair  value.  The  measurement  provisions  of this
statement apply  prospectively  to guarantees  issued or modified after December
31,  2002.  The  disclosure  provisions  of the  statement  apply  to  financial
statements  for periods  ending after December 15, 2002. The adoption of FIN No.
45 did not have a material impact on the Company's financial position or results
of operations.

In January 2003, the FASB issued FIN No. 46, "Consolidation of Variable Interest
Entities." FIN 46 requires a company to consolidate  variable interest entity if
it is designated as the primary  beneficiary  of that entity even if the company
does  not have a  majority  voting  interest.  A  variable  interest  entity  is
generally  defined  as an entity  where its  equity  is  unable to  finance  its
activities  or when the  owners  of the  entity  lack the  risk and  rewards  of
ownership.  The provisions of this  statement  apply at inception for any entity
created after January 31, 2003. For an entity  created before  February 1, 2003,
the  provisions of this  interpretation  must be applied at the beginning of the
first  interim or annual  period  beginning  after June 15,  2003.  The  Company
believes that the adoption of FIN No. 46 will not have a material  impact on its
financial position or results of operations.

3.       INVENTORIES (AMOUNTS IN THOUSANDS):

                                                  MARCH 31,         DEC. 31,
                                                    2003              2002
                                                   ------            ------

     Raw materials ....................            $2,812             2,703
     Work in process ..................               622               493
     Finished goods ...................             6,049             5,684
                                                   ------            ------
                                                   $9,483             8,880
                                                   ======            ======

4.       PROPERTY AND EQUIPMENT (AMOUNTS IN THOUSANDS):

                                                  MARCH 31,       DEC. 31,
                                                    2003            2002
                                                  --------        --------

     Machinery and equipment ..............       $  9,207           9,241
     Office furniture and equipment .......          3,857           3,708
     Leasehold improvements ...............          1,657           1,530
                                                  --------        --------
                                                    14,721          14,479
     Less accumulated depreciation and
        amortization ......................         (7,535)         (7,081)
                                                  --------        --------
                                                  $  7,186           7,398
                                                  ========        ========


                                       7





5.   GOODWILL AND INTANGIBLE ASSETS - ADOPTION OF FINANCIAL ACCOUNTING STATEMENT
     142

The Company  implemented  Financial  Accounting  standard ("FAS") 141 and 142 in
January 2002. In the first  quarter of 2002,  the Company  recognized a non-cash
charge,  net  of  applicable  income  taxes,  of  $2,870,000   representing  the
cumulative  effect  of a  change  in  accounting  principle  resulting  from the
implementation  of FAS 142.  The  charge  included  the  write off of all of the
goodwill related to the acquisition of Quality Controlled  Biochemicals  ("QCB")
and  Biofluids  in  December  1998.  The  Company  continues  to  carry  certain
identifiable  intangible assets with definite useful lives on its balance sheet.
The  amortization  associated  with  these  identifiable  intangible  assets was
approximately  $145,000 and  $160,000 for the quarters  ended March 31, 2003 and
2002, respectively.

6.   STOCK OPTIONS, PURCHASE PLANS AND WARRANTS

The  Company  currently  has two stock  option  plans in place - the 1993  Stock
Incentive  Plan (the "1993  Plan") and the 2000 BSI  non-qualified  stock option
Plan (the "2000  Plan").  The Company also has several  stock option  agreements
with certain officers in effect.

Under the 2000 Plan,  non-qualified  stock  options may be granted to  full-time
employees,  part-time  employees,  directors and  consultants  of the Company to
purchase a maximum of 2,000,000  shares of the company's  common stock.  Options
granted  under the 2000 Plan vest and are generally  exercisable  at the rate of
25% each  year  beginning  one year from the date of  grant.  The stock  options
generally expire ten years from the date of grant.

Under the 1993 Plan, incentive and non-qualified stock options may be granted to
full-time  employees,  part-time  employees,  directors and  consultants  of the
Company to  purchase  a maximum of  2,000,000  shares of common  stock.  Options
granted  under the 1993 Plan vest and are generally  exercisable  at the rate of
25% each  year  beginning  one year from the date of  grant.  The stock  options
generally expire ten years from the date of grant.

The Company applies APB Opinion No. 25 in accounting for its stock option grants
to employees and  directors,  and  accordingly,  no  compensation  cost has been
recognized for its stock options in the consolidated financial statements as the
market value of the Company's common stock at the date of grant was equal to its
exercise price on such date. Had the Company determined  compensation cost based
upon the fair value at the grant date for its stock  options under SFAS No. 123,
the  Company's  net income  (loss) would have  changed to the pro forma  amounts
indicated below:

                                                    Three Months Ended March 31,
                                                         2003             2002
                                                     -----------     ----------
                                           (in thousands, except per share data)
NET INCOME (LOSS):
     As reported ..............................      $       103         (2,499)
        Add/deduct: Total stock-based employee
        compensation expense determined under
        intrinsic value based method for all
        awards, net of tax effects ............             --             --
        Deduct: Total stock-based employee
        compensation expense determined under
        fair value based method for all awards,
        net of tax effects ....................             (278)          (542)
                                                     -----------     ----------

     Pro forma net loss available to common
        shareholders ..........................      $      (175)        (3,041)
                                                     ===========     ==========

Net income (loss) per share:
     Basic - as reported ......................      $      0.01          (0.25)
                                                     ===========     ==========

     Basic - pro forma ........................      $     (0.02)         (0.30)
                                                     ===========     ==========

     Diluted - as reported ....................      $      0.01          (0.23)
                                                     ===========     ==========

     Diluted - pro forma ......................      $     (0.02)         (0.30)
                                                     ===========     ==========


                                       8





7.   EARNINGS PER SHARE

The  reconciliation  of basic to diluted  weighted  average shares is as follows
(amounts in thousands):

                                                            THREE MONTHS ENDED
                                                                  MARCH 31,
                                                            2003           2002
                                                           ------         ------

Weighted average shares used in basic
   computation ...................................          9,635         10,190

Dilutive stock options and warrants ..............            391            567
                                                           ------         ------

Weighted average shares used for diluted
   computation ...................................         10,026         10,757
                                                           ======         ======


Options to purchase  1,036,962  and  1,241,848  shares were not  included in the
computation  of diluted net income per share for the three month  periods  ended
March  31,  2003  and  2002,   respectively   because   their  effect  would  be
anti-dilutive.

Warrants to purchase  1,287,000  shares at a weighted  average exercise price of
$7.77  per share  were  outstanding  as of March 31,  2003 and 2002 but were not
included in the computation of diluted net income per share for the three months
ended March 31, 2003 and 2002 because their effect would be anti-dilutive.

8.   STOCKHOLDERS' EQUITY

Comprehensive income (loss) is determined as follows (amounts in thousands):

                                                        THREE MONTHS ENDED
                                                             MARCH 31,
                                                        2003           2002
                                                     ---------       --------

Net income (loss) .............................      $     103         (2,449)
Foreign currency translation adjustments ......            240             (3)
                                                     ---------       --------
Total comprehensive income (loss) .............      $     343         (2,502)
                                                     =========       ========

9.   BUSINESS SEGMENTS

The  Company  is  engaged  in a single  industry,  the  licensing,  development,
manufacture, marketing and distribution of immunological reagents, test kits and
oligonucleotides  used  in  biomedical  research  and  human  diagnostics.   Our
customers are not concentrated in any specific  geographic  region and no single
customer accounts for a significant amount of our sales.

Management of the Company has determined  its reportable  segments are strategic
business  units  that offer both sales to  external  customers  from  geographic
company  facilities  and  sales to  external  customers  in  certain  geographic
regions.  Significant  reportable  business  segments are the United  States and
European  facilities,  and sales to external  customers are  summarized as those
located in the United States,  Europe,  Japan and other. We evaluate performance
for  the  "Sales-from"  segments  on  net  revenue  and  profit  and  loss  from
operations.  Our  reportable  segments are strategic  business  units that offer
geographical  product  availability.  They are managed  separately  because each
business  requires  different  marketing and distribution  strategies.  Business
information is summarized as follows:


                                       9





                                                    THREE MONTHS ENDED
                                                         MARCH 31,
                                                  2003              2002
                                               -----------      ----------
SALES - FROM SEGMENTS (IN THOUSANDS):
Net sales to external customers from:
     United States:
         Domestic                              $     6,027      $    5,895
         Export                                      1,116           1,106
                                               -----------      ----------
                Total United States                  7,143           7,001
     Europe                                          3,756           2,780
                                               -----------      ----------
                Consolidated                   $    10,899      $    9,781
                                               ===========      ==========

Operating income (loss):
     United States                             $      (737)     $     (233)
     Europe                                            858             639
                                               -----------      ----------
                Consolidated                   $       121      $      406
                                               ===========      ==========

SALES - TO SEGMENTS (IN THOUSANDS):
Net sales to external customers in:
     United States                             $     6,027      $    5,895
     Europe                                          3,286           2,451
     Japan                                             906             932
     Other                                             680             503
                                               -----------      ----------
                Consolidated                   $    10,899      $    9,781
                                               ===========      ==========

SALES - BY PRODUCT GROUP
Net sales by product group:
     Cytokine                                  $     4,877      $    4,566
     Signaling                                       2,430           1,495
     Custom                                          3,592           3,720
                                               -----------      ----------
                Consolidated                   $    10,899      $    9,781
                                               ===========      ==========


ITEM 2. MANAGEMENT'S  DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS
        OF OPERATIONS

This  discussion  and analysis of financial  condition and results of operations
should be read in conjunction with the consolidated  financial  statements,  the
notes thereto and other information, including information set forth in our 10-K
for the fiscal year ended  December  31, 2002,  and all other recent  filings we
have made with the Securities and Exchange Commission.

This Form 10-Q contains forward-looking  statements,  which are made pursuant to
the safe-harbor  provisions of the Private  Securities  Litigation Reform Act of
1995.   Within   this  Form  10-Q,   words  such  as   "believes,"   "designed,"
"anticipates," and similar expressions are intended to identify  forward-looking
statements,  but are not the exclusive  means of  identifying  such  statements.
These  forward-looking  statements  involve a number of risks and uncertainties,
including  the timely  development  and market  acceptance  of our  products and
technologies  and other factors  described  throughout this Form 10-Q and in our
other filings with the  Securities and Exchange  Commission.  The actual results
that we achieve may differ from any forward-looking statements due to such risks
and  uncertainties.  We do not undertake any  obligation to revise or update any
forward-looking  statements in order to reflect events or circumstances that may
arise after the date of this report.

OVERVIEW

Our  Company  develops,  manufactures,  markets  and  distributes  products  and
services that are widely used in biomedical research.  Our products and services
enable  scientists to better  understand the  biochemistry,  immunology and cell
biology of the human body, aging and certain diseases such as cancer,  arthritis
and other inflammatory diseases,  AIDS and certain other infectious diseases. We
have a wide  variety of  products,  including  immunoassay  and ELISA test kits;
immunological reagents, including bioactive proteins (cytokines,  growth factors
and  adhesion  molecules),   oligonucleotides,  and  monoclonal  and  polyclonal
antibodies. We also manufacture and market custom oligonucleotides, peptides and
antibodies  to the  specifications  of our  customers.  We use  recombinant  DNA
technology  to produce  cytokines and other  proteins.  We have  registered  our
analyte specific reagents with the FDA and have received a license to sell these
products  as Class I Medical  Devices.  We  market  these  products  to IN VITRO
diagnostic   manufacturers  and  clinical  reference   laboratories  as  "active
ingredients" in the tests they produce to


                                       10





identify  various  specific  diseases or  conditions.  In order to market  these
products as medical devices,  we are required to be in compliance with the FDA's
Current Good Manufacturing Practices and Regulations.

CRITICAL ACCOUNTING POLICIES

General

Our discussion and analysis of our financial condition and results of operations
are based upon our consolidated  financial statements,  which have been prepared
in  accordance  with  accounting  principles  generally  accepted  in the United
States.  The  preparation  of these  financial  statements  requires  us to make
estimates and judgments that affect the reported amounts of assets, liabilities,
revenues  and  expenses,   and  related  disclosure  of  contingent  assets  and
liabilities.  On an on-going  basis,  the Company  evaluates its estimates.  The
Company  bases its  estimates  on  historical  experience  and on various  other
assumptions  that are believed to be  reasonable  under the  circumstances,  the
results of which form the basis for making  judgments  about the carrying values
of assets and  liabilities  that are not readily  apparent  from other  sources.
Actual results may differ from these estimates  under  different  assumptions or
conditions. Specifically, management must make estimates in the following areas:

     ALLOWANCE FOR DOUBTFUL ACCOUNTS.

     The Company has $7,393,000 in gross trade accounts  receivable and $264,000
     in allowance  for doubtful  accounts on the  consolidated  balance sheet at
     March 31, 2003.  The Company has  procedures in place to adequately  review
     the credit  worthiness of new customers and also to properly  review orders
     from  existing  customers  to  determine  if a change  in  credit  terms is
     warranted.  A review of our allowance for doubtful  accounts is done timely
     and  consistently  throughout  the year.  As of March 31,  2003 the Company
     believes its allowance for doubtful accounts is fairly stated.  The Company
     does have accounts  receivable  amounts from certain  customers as of March
     31,  2003  that if their  financial  condition  changed  and a  significant
     allowance needed to be created, could have a material adverse effect on the
     Company's financial results for 2003.

     INVENTORY ADJUSTMENTS.

     The Company  reviews the components of our inventory on a regular basis for
     excess, obsolete and impaired inventory based on estimated future usage and
     sales.  The  manufacturing  process for  antibodies has and may continue to
     produce quantities substantially in excess of forecasted usage, if any, and
     anticipated  antibody sales volumes are highly uncertain and realization of
     individual  product cost may not occur. As a result,  the Company  reserves
     its entire  manufactured  antibody  inventory  at 100% of its value.  As of
     March 31, 2003,  the Company had $4,663,000 of  manufactured  antibodies in
     its inventory and a reserve for these antibodies totaling  $4,663,000.  The
     Company will  continue to monitor its antibody  inventory and the continued
     need for a 100% reserve.  Additionally,  material inventory  write-downs in
     our  inventory  can  occur  if   competitive   conditions  or  new  product
     introductions by our customers or us vary from our current expectations.

     DEFERRED TAX ASSETS AND DEFERRED INCOME TAXES.

     The  Company  has   $10,683,000  in  deferred  income  tax  assets  on  its
     consolidated  balance  sheet as of March 31, 2003. As of March 31, 2003, no
     valuation  allowance  has been set up to  offset  any of the  deferred  tax
     assets.  The ability to realize these deferred tax assets depends  entirely
     on the Company  generating  taxable  income in the future.  The Company has
     used  historical  information as well as a projected  financial  outlook to
     project taxable income amounts. The Company believes it is more likely than
     not that they will be able to  realize  these  benefits  in the  future.  A
     material change in our expected  realization of these assets would occur if
     the ability to deduct tax loss carryforwards  against future taxable income
     is  altered.  If our  projections  involving  tax  planning  and  operating
     strategies do not  materialize or if significant  changes in tax laws occur
     within the various tax jurisdictions in which we operate,  we would have to
     set up a valuation  allowance  against our  deferred  tax assets that could
     materially effect our tax expense and our financial results.


                                       11





     The Company believes the following critical  accounting policies affect our
     more  significant  judgements  and  estimates  used in  preparation  of our
     consolidated financial statements.

     REVENUE  RECOGNITION.  The Company's  revenue is generated from the sale of
     products primarily manufactured  internally.  The Company does have a small
     amount of products that are sold on an outside equipment ("OEM") basis. The
     Company  sells  standard  and  custom  products  directly  to end users and
     distributors and recognizes revenue upon transfer of title to the customer,
     which occurs upon shipment. General sales and payment terms to distributors
     are  similar  to those  granted  to end user  customers.  Certain  end user
     customers  prepay for product and request shipment of the product at future
     dates,  primarily  sera or media  products.  The Company  records  deferred
     revenue   until  such  time  as  a  product  is  shipped  to  a   customer.
     Approximately  25% of the  Company's  net sales for the three  months ended
     March 31, 2003 were to  distributors  compared to 23% for the three  months
     ended March 31, 2002. The Company's distribution  agreements do not provide
     a general right of return.  The amount of the Company's  inventory  held by
     distributors is not believed to be substantial.

     The Securities and Exchange Commission's Staff Accounting Bulletin No. 101,
     "Revenue  Recognition," ("SAB 101") provides guidance on the application of
     generally accepted  accounting  principles to selected revenue  recognition
     issues.  The  Company  believes  that its  revenue  recognition  policy  is
     consistent  with this guidance and in accordance  with  generally  accepted
     accounting  principles.  We do not  anticipate  any  changes to our revenue
     recognition and shipping policies in the future.

     LONG-LIVED  ASSETS. It is our policy,  and in accordance with SFAS No. 144,
     to account for long-lived assets, including intangibles, at amortized cost.
     As  part  of an  ongoing  review  of  the  valuation  and  amortization  of
     long-lived assets, management assesses the carrying value of such assets if
     facts and circumstances  suggest that they may be impaired.  If this review
     indicates that long-lived assets will not be recoverable,  as determined by
     a non-discounted cash flow analysis over the remaining amortization period,
     the carrying value of the Company's  long-lived  assets would be reduced to
     its estimated fair value based on discounted cash flows.  As a result,  the
     Company has determined  that its  long-lived  assets are not impaired as of
     March 31, 2003.

     GOODWILL.  FAS No. 141 requires  that the purchase  method of accounting be
     used for all business  combinations  initiated after June 30, 2001. FAS No.
     142 requires that goodwill and  intangible  assets with  indefinite  useful
     lives no longer be  amortized  to  earnings,  but instead be  reviewed  for
     impairment in accordance with FAS No. 142.  Effective  January 1, 2002, the
     Company's  goodwill and other intangible assets are accounted for under FAS
     No.  141  "Business  Combinations"  and FAS No.  142  "Goodwill  and  Other
     Intangible   Assets."  The  Company  used  the  present  value  method  for
     determining the fair value of its reporting  units. In the first quarter of
     2002, the Company  recognized a non-cash charge,  net of applicable  income
     taxes,  of $2,870,000  representing  the  cumulative  effect of a change in
     accounting  principle  resulting  from the  implementation  of FAS 142. The
     charge  included  the  write  off of all of  the  goodwill  related  to the
     acquisition  of Quality  Controlled  Biochemicals  ("QCB") and Biofluids in
     December  1998.  The  Company  continues  to  carry  certain   identifiable
     intangible  assets with  definite  useful lives on its balance  sheet.  The
     amortization  associated  with  these  identifiable  intangible  assets was
     approximately  $145,000 and $160,000 for the quarters  ended March 31, 2003
     and 2002, respectively.

     The Company  reviewed its  remaining  goodwill for  impairment in the third
     quarter of 2002 and  determined  that the carrying  value was not impaired.
     Accordingly,  the Company  continues to carry the  goodwill  related to its
     1996  acquisition  of certain  assets and assumed  liabilities  of Medgenix
     Diagnostics,  SA, now BioSource Europe, S.A., a wholly-owned  subsidiary of
     the Company, on its Consolidated Balance Sheets.

     ADVERTISING  COSTS.  In the  quarter  ended  March 31,  2003,  the  Company
     capitalized its annual catalog  production  costs. In the past, the Company
     has expensed catalog  production costs as incurred,  which was primarily in
     the first quarter of its fiscal year.  During 2002, and after production of
     the catalog,  the Company put substantial effort into increasing the number
     of customers in its customer  database and in  conjunction  with that,  its
     dependence  on its  catalog to attract  more  customers.  As a result,  the
     Company believes that their 2003 catalog is a direct response advertisement
     whose  primary  purpose  is  to  elicit  sales  to  customers  who  respond
     specifically to the catalog  resulting in probable future economic benefit.



                                       12





     Accordingly,  beginning in 2003,  the Company is  capitalizing  its catalog
     production  costs and expensing  them evenly  throughout the fiscal year in
     accordance  with the  AICPA's  Statement  of Position  93-07.  In the first
     quarter of 2002,  the Company  expensed  approximately  $359,000 of catalog
     costs  compared to $113,000 for the first quarter of 2003. The Company does
     not  anticipate  its annual  catalog costs to be materially  different from
     2002 to 2003.

CONSOLIDATED RESULTS OF OPERATIONS FOR THE THREE MONTHS ENDED MARCH 31, 2003

REVENUES:  Net sales for the quarter ended March 31, 2003 were $10.9 million, an
increase of $1.1 million,  or 11% (5% after  eliminating  the $551,000  positive
impact of foreign  exchange),  compared to net sales for the quarter ended March
31, 2002. The Company's  increased sales and marketing  expenditures,  including
increased  catalog  distribution,  and its continued  investment in research and
development  activities  resulting in new  products for sale,  have been primary
drivers for sales growth in North America and Europe.

To  better  drive  sales  and  profitability  growth  and  focus  on key  market
opportunities  the Company has divided its business  into three core areas:  The
Strategic  Business Units ("SBU's") of Signal  Transduction  Products,  Cytokine
Products,  and Custom  Products.  Signal  Transduction  Products  consist of the
proteins,  antibodies, assays and other reagents used to study internal cellular
processes. Our phosphospecific  antibodies and phosphoELISA(TM)s are included in
this SBU. Cytokine Products include the proteins,  anitbodies,  assays and other
reagents  that are used to  study  the  processes  by which  cells  communicate.
Interleukin,  growth factor and other biological  response modifier products are
included  in this  group.  Custom  Products  includes  oligonucleotides,  custom
peptides and  antibodies,  cell culture and  diagnostics  and other reagents not
specifically categorized.

For the three months ended March 31, 2003,  the  Company's  Signal  Transduction
Products,  grew  62%  compared  to  the  comparable  prior  year  quarter,  from
$1,495,000 to $2,430,000.  Signal Transduction Products represent  approximately
22% of our total  sales for the three  months  ended  March 31,  2003 and 15% of
sales for the three months ended March 31, 2002. The Company believes the signal
transduction  market is growing and has opportunities for continued  significant
sales growth in this market. The Company's sales growth in its Cytokine Products
for the quarter  ending March 31, 2003 was 7%,  increasing  from  $4,566,000  to
$4,877,000,  compared to the three  months  ended March 31,  2002.  The cytokine
product  line  represents  approximately  45% of our total sales for the quarter
ended March 31, 2003 compared to 47% for the quarter  ended March 31, 2002.  The
Cytokine market is a mature market which the Company believes  continues to have
opportunities for solid sales growth.  The Company's Custom Product lines, which
represents  approximately  33% of our total sales,  decreased 3% compared to the
comparable prior year quarter, from $3,720,000 to $3,592,000. The custom product
line represents approximately 38% of our total sales for the quarter ended March
31,  2002.  The  custom  product  line  was  impacted  by  declining   sales  in
oligonucleotides, which was offset by increasing sales in diagnostic products.

For the three months ended March 31, 2003, the Company achieved net sales growth
in North  America of 2% as compared to the three  months  ended March 31,  2002.
European  sales for the three months ended March 31, 2003  increased 34% (13% in
local currency), as compared to the comparable prior year period. Sales in Japan
and the rest of the world  increased  11%,  for the three months ended March 31,
2003 as compared to the three months ended March 31, 2002

GROSS PROFIT:  Gross profit margin was 57% for both the three months ended March
31, 2003 and 2002. The Company's  margins  remained  constant in part due to the
continued  investment  in  production  and  planning  related  areas  within the
Company.  The Company's margins in its cytokine and signaling core product lines
continue to be strong.  The margins in our custom product lines have limited our
overall gross margin improvement.

RESEARCH AND DEVELOPMENT:  Research and development expense for the three months
ended March 31, 2003 and 2002 were $1,979,000 and $1,293,000 and represented 18%
and 13% of  sales,  respectively.  The  increase  in  research  and  development
expenses  for the three  months  ended  March  31,  2003  when  compared  to the
comparable  prior year period reflects the Company's  incremental  investment in
additional  personnel  and  materials in the  cytokine  and signal  transduction
research  areas.  The Company has made a  significant  investments  in its R & D
capabilities over the past 15 months. The result of this investment has been the
release  of  significantly  more and  higher  quality  and novel  products,  and
resulted in increased  sales in both the cytokine and signaling  product  lines.


                                       13





Quarterly  expenditures  in R&D for the  remainder  of 2003 are  expected  to be
slightly  less than  those in the first  quarter of 2003.

SALES AND  MARKETING:  Selling and marketing  expenses were $2.4 million for the
three  months  ended March 31, 2003 and $2.3  million for the three months ended
March 31, 2002, representing 22% and 23% of sales, respectively. The increase is
due to additional investment in personnel and marketing programs.

In the quarter ended March 31, 2003, the Company  capitalized its annual catalog
production costs. In the past, the Company has expensed catalog production costs
as incurred, which was primarily in the first quarter of its fiscal year. During
2002, and after  production of the catalog,  the Company put substantial  effort
into  increasing  the  number  of  customers  in its  customer  database  and in
conjunction  with that, its dependence on its catalog to attract more customers.
As a result,  the Company  believes that their 2003 catalog is a direct response
advertisement  whose primary purpose is to elicit sales to customers who respond
specifically  to the catalog  resulting  in probable  future  economic  benefit.
Accordingly,  beginning  in  2003,  the  Company  is  capitalizing  its  catalog
production  costs and  expensing  them  evenly  throughout  the  fiscal  year in
accordance with the AICPA's Statement of Position 93-07. In the first quarter of
2002, the Company expensed  approximately  $359,000 of catalog costs compared to
$113,000  for the first  quarter of 2003.  The Company does not  anticipate  its
annual catalog costs to be materially different from 2002 to 2003.

GENERAL  AND  ADMINISTRATIVE:  General  and  administrative  expenses  were $1.6
million for the three  months  ended March 31,  2003,  and $1.5  million for the
three months ended March 31, 2002, a increase of  approximately  $100,000.  As a
percentage of sales, general and administrative expenses represented 14% and 15%
for the three months ended March 31, 2003 and 2002, respectively.

AMORTIZATION OF INTANGIBLE  ASSETS L: Amortization of intangible assets for each
of the three  months  ended  March 31, 2003 and 2002  amounted  to $145,000  and
$160,000,  respectively  and is related  primarily  to the  amortization  of the
identifiable   intangible  assets  from  the  QCB  and  Biofluids   acquisitions
transacted in 1998.

INTEREST  INCOME:  Interest income for the three months ended March 31, 2003 and
2002,  was  $11,000  and  $40,000,  respectively,  which was related to interest
income on cash invested in short-term  securities  during each of the respective
quarters.

INCOME TAX EXPENSE: The effective tax rate for the three months ending March 31,
2003 was 10%. The Company is  benefiting  from R & D and other tax credits which
when  applied  to income  levels  for the  periods  presented  is  resulting  in
effective  tax  rates  lower  than the  current  applicable  federal  and  state
statutory rates. The Company has elected to utilize the Extraterritorial  Income
Exclusion ("EIE") federal tax credit,  which, along with other tax credits,  has
reduced its effective tax rate for 2003 to 10%. The Company's effective tax rate
is reviewed and evaluated quarterly and may change depending on certain factors,
including, among other things, the income level of the Company.

LIQUIDITY AND CAPITAL RESOURCES:

Cash and cash  equivalents  as of March 31,  2003,  of  $3,840,000  decreased by
$2,101,000  from  $5,941,000  at December  31,  2002.  The  decrease in cash was
partially  due from a cash  outlay of  $662,000  for the  repurchase  of 110,000
shares of the  Company's  common  stock  through  its stock  repurchase  program
initiated in October 2001.  Net cash used in operating  activities of $1,227,000
was augmented by capital expenditures of $238,000 and net cash used in financing
activities of $571,000.  Working capital,  which is the excess of current assets
over current  liabilities,  was  $16,714,000  at March 31, 2003,  as compared to
$16,596,000 at December 31, 2002, representing an increase of $118,000.

In the three months ended March 31, 2003, the Company  received $95,000 from the
issuance of common stock related to the exercise of stock  options.  The Company
spent  $238,000  on capital  expenditures,  primarily  used for the  purchase of
laboratory and manufacturing equipment.

In  October of 2001,  the  Company  announced  that its Board of  Directors  had
approved a stock repurchase program. The Board originally authorized the Company
to repurchase  up to $5 million of its common stock and have the


                                       14





program  expire  on  June  30,  2003.  The  repurchases  are to be  made  at the
discretion  of  management  and can be made at any time,  as  market  conditions
warrant.  On July 19, 2002, the Company amended the stock repurchase program and
increased its repurchase  commitment by $5 million to a total of $10 million. On
April 22, 2003, the Company again amended the stock repurchase program extending
the expiration  date of the Company's  current program from June 2003 until June
2004.  In  addition,  the Board  approved  adding $5 million to its  current $10
million dollar allowable repurchase commitment,  bringing the total limit to $15
million.  In the first quarter of 2003, the Company spent $666,000  repurchasing
110,000 shares of its common stock under its stock repurchase program,  bringing
the total number of shares  repurchased  since October 2001 to 989,000 and total
cash outlays to $5.9 million.  All 989,000  shares have been  retired.  This has
contributed to the reduction in weighted average diluted shares  outstanding for
the three months ended March 31, 2003 to 10,026,000  compared to the  10,757,000
diluted shares for the three months ended March 31, 2002. Since  inception,  the
company  has  repurchased  9% of  its  outstanding  common  stock.  The  Company
continues to believe its common stock is  undervalued  and feels it is important
to have the availability to repurchase outstanding shares of its common stock at
any time.

The Company has never paid  dividends  on common stock and has no plans to do so
in fiscal 2003. Our earnings will be retained for reinvestment in the business.

The  Company  expects to be able to meet its  future  cash and  working  capital
requirements for operations and capital additions  through  currently  available
funds  and  cash  generated  from  operations,  if any.  However,  we may  raise
additional  capital or secure debt financing from time to time to take advantage
of  favorable  conditions  in the  market or in  connection  with our  corporate
development activities.


                                       15





                                  RISK FACTORS

You  should  carefully  consider  the  following  risk  factors  and  all  other
information  contained  in this report  before  purchasing  shares of our common
stock.  Investing in our common stock  involves a high degree of risk. If any of
the following events or outcomes actually occur, our business, operating results
and financial  condition would likely suffer. As a result,  the trading price of
our common  stock could  decline,  and you may lose all or part of the money you
paid to purchase our common stock.

                          RISKS RELATED TO OUR BUSINESS

FAILURE TO MANAGE OUR GROWTH AND EXPANSION COULD IMPAIR OUR BUSINESS.

We  historically  have sought,  and will continue to seek, to increase our sales
and profitability  primarily through the acquisition or internal  development of
new product  lines,  additional  customers and new  businesses.  Our  historical
revenue growth is primarily  attributable  to our  acquisitions  and new product
development  and, to a lesser  extent,  to increased  revenues from our existing
products. We expect that future acquisitions,  if successfully consummated, will
create  increased  working  capital  requirements,  which will likely precede by
several  months any material  contribution  of an acquisition to our net income.
Our  ability  to  achieve  our  expansion  objectives  and to manage  our growth
effectively and profitably depends upon a variety of factors, including:

o    our ability to internally develop new products;

o    our ability to make profitable acquisitions;

o    integration of new facilities into existing operations;

o    hiring, training and retention of qualified personnel;

o    establishment of new  relationships or expansion of existing  relationships
     with customers and suppliers; and

o    availability of capital.

In addition,  the  implementation  of our growth strategy will place significant
strain on our administrative,  operational and financial resources and increased
demands on our financial systems and controls.  Our ability to manage our growth
successfully  will require us to continue to improve and expand these resources,
systems and controls.  If our management is unable to manage growth effectively,
our operating  results could be adversely  affected.  Moreover,  there can be no
assurance that our historic rate of growth will continue,  that we will continue
to successfully expand or that growth or expansion will result in profitability.

WE CANNOT GUARANTEE THAT OUR FUTURE ACQUISITIONS WILL BE SUCCESSFUL.

We compete for acquisition and expansion opportunities with companies which have
significantly  greater financial and management  resources than us. There can be
no assurance  that  suitable  acquisition  or investment  opportunities  will be
identified,  that any of these  transactions  can be  consummated,  or that,  if
acquired,  these new  businesses can be integrated  successfully  and profitably
into our  operations.  These  acquisitions  and  investments  may also require a
significant  allocation of resources,  which will reduce our ability to focus on
the other portions of our business,  including many of the factors listed in the
prior risk factor.

REDUCTION  OR DELAYS IN  RESEARCH  AND  DEVELOPMENT  BUDGETS  AND IN  GOVERNMENT
FUNDING MAY NEGATIVELY IMPACT OUR SALES.

Our customers include researchers at pharmaceutical and biotechnology companies,
academic institutions and government and private  laboratories.  Fluctuations in
the  research  and   development   budgets  of  these   researchers   and  their
organizations  could have a  significant  effect on the demand for our products.
Research and  development  budgets  fluctuate  due to numerous  factors that are
outside our control and are difficult to predict, including changes in available
resources,   spending  priorities  and  institutional  budgetary  policies.  Our
business could be seriously


                                       16





damaged by any  significant  decrease in life sciences  research and development
expenditures   by   pharmaceutical   and   biotechnology   companies,   academic
institutions or government and private laboratories.

A  significant  portion  of our  sales  has been to  researchers,  universities,
government  laboratories and private foundations whose funding is dependent upon
grants from government  agencies such as the U.S. National  Institutes of Health
(the "NIH") and similar domestic and international agencies.  Although the level
of research  funding has  increased  during the past  several  years,  we cannot
assure  that this trend  will  continue.  Government  funding  of  research  and
development is subject to the political  process,  which is inherently fluid and
unpredictable.  Our revenues may be adversely  affected if our  customers  delay
purchases as a result of  uncertainties  surrounding  the approval of government
budget proposals.  Also,  government  proposals to reduce or eliminate budgetary
deficits  have  sometimes  included  reduced  allocations  to the NIH and  other
government agencies that fund research and development  activities.  A reduction
in government  funding for the NIH or other government  research  agencies could
seriously damage our business.

Many of our customers  receive funds from approved grants at particular times of
the year,  as determined  by the federal  government.  Grants have, in the past,
been frozen for extended periods or have otherwise become unavailable to various
institutions  without advance  notice.  The timing of the receipt of grant funds
affects the timing of purchase  decisions by our customers and, as a result, can
cause fluctuations in our sales and operating results.

WE RELY ON RAW MATERIALS AND SPECIALIZED EQUIPMENT FOR OUR MANUFACTURING,  WHICH
WE MAY NOT ALWAYS BE ABLE TO OBTAIN ON FAVORABLE TERMS.

Our manufacturing  process relies on the continued  availability of high-quality
raw  materials  and  specialized  equipment.  It is  possible  that a change  in
vendors,  or in the quality of the raw  materials  supplied to us, could have an
adverse impact on our manufacturing process and, ultimately,  on the sale of our
finished  products.  We have from time to time  experienced  a disruption in the
quality or availability of key raw materials,  which has created minor delays in
our ability to fill orders for specific test kits. This could occur again in the
future,  resulting in significant delays, and could have a detrimental impact on
the sale of our products and our results of operations.  In addition, we rely on
highly  specialized  manufacturing  equipment  that if damaged or disabled could
adversely   affect  our  ability  to  manufacture  our  products  and  therefore
negatively  impact  our  business.  We  rely  on  the  timely  transport  of raw
materials. Any disruption in transportation systems could have an adverse impact
on our ability to manufacture and supply products.

OUR ABILITY TO RAISE THE CAPITAL NECESSARY TO EXPAND OUR BUSINESS IS UNCERTAIN.

In the future,  in order to expand our business through internal  development or
acquisitions,  we may need to raise substantial  additional funds through equity
or  debt  financings,  research  and  development  financings  or  collaborative
relationships.  However,  this  additional  funding may not be available  or, if
available,  it  may  not be  available  on  economically  reasonable  terms.  In
addition,  any additional funding may result in significant dilution to existing
stockholders. If adequate funds are not available, we may be required to curtail
our operations or obtain funds through  collaborative  partners that may require
us to release material rights to our products.

OUR RESEARCH AND DEVELOPMENT EFFORTS FOR NEW PRODUCTS MAY BE UNSUCCESSFUL.

We incur significant  research and development  expenses to develop new products
and  technologies.  There  can be no  assurance  that any of these  products  or
technologies  will be  successfully  developed  or that  if  developed,  will be
commercially   successful.   In  the  event   that  we  are  unable  to  develop
commercialized  products  from our  research and  development  efforts or we are
unable or  unwilling  to  allocate  amounts  beyond  our  currently  anticipated
research and  development  investment,  we could lose our entire  investment  in
these new  products  and  technologies.  Any failure to  translate  research and
development expenditures into successful new product introductions could have an
adverse effect on our business.


                                       17





FAILURE TO LICENSE NEW TECHNOLOGIES COULD IMPAIR OUR NEW PRODUCT DEVELOPMENT.

Our business model of providing products to researchers  working on a variety of
genetic projects requires us to develop a wide spectrum of products. To generate
broad product lines it is advantageous to sometimes  license  technologies  from
others rather than depending  exclusively on our own employees.  As a result, we
believe our ability to license new  technologies  from third parties is and will
continue to be important to our ability to offer new products.

In  addition,  from time to time we are notified or become aware of patents held
by third parties that are related to  technologies we are selling or may sell in
the future.  After a review of these patents,  we may decide to obtain a license
for these  technologies  from these third parties or  discontinue  the products.
There  can be no  assurance  that we will be able to  continue  to  successfully
identify new technologies  developed by others.  Even if we are able to identify
new  technologies  of  interest,  we may not be able to  negotiate  a license on
favorable terms, or at all. If we lose the rights to patented technology, we may
need to discontinue  selling certain  products or redesign our products,  and we
may  lose  a  competitive  advantage.  Potential  competitors  could  in-license
technologies  that we fail to license and potentially erode our market share for
certain   products.    Our   licenses    typically   subject   us   to   various
commercialization,  sublicensing,  minimum payment, and other obligations. If we
fail to comply with these  requirements,  we could lose important rights under a
license. In addition, certain rights granted under the license could be lost for
reasons  out of our  control.  For  example,  the  licensor  could  lose  patent
protection for a number of reasons, including invalidity of the licensed patent.
We do not always receive  significant  indemnification  from a licensor  against
third party claims of intellectual property infringement.

We are  currently in the process of  negotiating  several of these  licenses and
expect that we will also negotiate these types of licenses in the future.  There
can be no  assurances  that  we will be able  to  negotiate  these  licenses  on
favorable terms, or at all.

OUR FUTURE SUCCESS  DEPENDS ON THE TIMELY  INTRODUCTION  OF NEW PRODUCTS AND THE
ACCEPTANCE OF THESE NEW PRODUCTS IN THE MARKETPLACE.

Our ability to gain access to technologies  needed for new products and services
also  depends  in  part  on  our  ability  to  convince  licensors  that  we can
successfully  commercialize  their inventions.  We cannot assure that we will be
able to continue to identify new  technologies  developed by others.  Even if we
are  able  to  identify  new  technologies  of  interest,  we may not be able to
negotiate a license on favorable terms, or at all.

IF WE FAIL TO INTRODUCE  NEW  PRODUCTS,  OR OUR NEW PRODUCTS ARE NOT ACCEPTED BY
POTENTIAL CUSTOMERS, WE MAY LOSE MARKET SHARE.

Rapid  technological  change and frequent new product  introductions are typical
for the markets we serve.  Our future success will depend in part on continuous,
timely development and introduction of new products that address evolving market
requirements.   We  believe  successful  new  product  introductions  provide  a
significant  competitive  advantage because customers make an investment of time
in  selecting  and  learning to use a new  product,  and then are  reluctant  to
switch. To the extent we fail to introduce new and innovative  products,  we may
lose market share to our  competitors,  which will be difficult or impossible to
regain.  Any inability,  for  technological  or other reasons,  to  successfully
develop and  introduce  new products  could reduce our growth rate or damage our
business.

In the past we have  experienced,  and are likely to  experience  in the future,
delays in the development and introduction of products. We cannot assure that we
will keep pace with the rapid rate of change in life sciences research,  or that
our new products will  adequately  meet the  requirements  of the marketplace or
achieve market  acceptance.  Some of the factors  affecting market acceptance of
new products include:

o    availability, quality and price relative to competitive products;

o    the timing of introduction of the product relative to competitive products;

o    customers' opinion of the products utility;


                                       18





o    ease of use;

o    consistency with prior practices;

o    scientists' opinion of the product's usefulness;

o    citation of the product in published research; and

o    general trends in life sciences research.

The  expenses  or  losses  associated  with  unsuccessful   product  development
activities  or lack of market  acceptance of our new products  could  materially
adversely affect our business,  operating results and financial  condition.  The
development,  introduction  and marketing of innovative  products in our rapidly
evolving markets will require significant sustained investment. We cannot assure
that cash from  operations  or other  sources will be  sufficient  to meet these
ongoing requirements.

FAILURE TO ATTRACT AND RETAIN  QUALIFIED  SCIENTIFIC OR PRODUCTION  PERSONNEL OR
LOSS OF KEY MANAGEMENT OR KEY PERSONNEL COULD HURT OUR BUSINESS.

Recruiting  and  retaining  qualified  scientific  and  production  personnel to
perform research and development  work and product  manufacturing is critical to
our success.  Because the industry in which we compete is very  competitive,  we
face significant  challenges  attracting and retaining this qualified  personnel
base.  Although  we believe we have been and will be able to attract  and retain
these  personnel,  there can be no assurance that we will be able to continue to
successfully  attract qualified personnel.  In addition,  our anticipated growth
and expansion into areas and activities requiring additional expertise,  such as
clinical testing,  government approvals,  production and marketing, will require
the addition of new  management  personnel  and the  development  of  additional
expertise by existing  management  personnel.  The failure to attract and retain
these personnel or,  alternatively,  to develop this expertise  internally would
adversely  affect  our  business.  We  generally  do not enter  into  employment
agreements  requiring  these  employees  to continue in our  employment  for any
period of time.

Our success also will continue to depend to a significant  extent on the members
of our management team and, in particular,  on our Chief  Executive  Officer and
President,  Leonard M.  Hendrickson.  We do not maintain any "key man" insurance
policies  regarding any of these  individuals.  We may not be able to retain the
services of our  executive  officers  and key  personnel  or attract  additional
qualified  members to  management  in the  future.  The loss of  services of Mr.
Hendrickson,  or of any of our other key  management or employees,  could have a
material adverse effect upon our business.

MANY OF OUR  CUSTOMERS  ARE  OBTAINING  OUR  PRODUCTS  THROUGH NEW  DISTRIBUTION
CHANNELS AND METHODS THAT MAY  ADVERSELY  IMPACT OUR RESULTS OF  OPERATIONS  AND
FINANCIAL CONDITION.

A number of our customers  have developed  purchasing  initiatives to reduce the
number of vendors they purchase  from in order to lower their supply  costs.  In
some cases, these customers have established  agreements with large distributors
which  include  discounts  and the  distributors'  direct  involvement  with the
purchasing process.  For similar reasons,  many larger customers,  including the
federal  government,  have  special  pricing  arrangements,   including  blanket
purchase  agreements.  These  agreements may limit our pricing  flexibility with
respect to our products,  which could adversely  impact our business,  financial
condition and results of operations. In addition, although we accept and process
some orders  through our Internet  website,  we also  implement  sales through a
third  party  Internet  vendor.   Internet  sales  through  third  parties  will
negatively  impact our gross margins because we pay commission on these Internet
sales. On the other hand, if we do not enter into  arrangements with third-party
e-commerce  providers,  we may lose  customers  who prefer to purchase  products
using these Web sites. Our business may be harmed as a result of these Web sites
or other sales methods which may be developed in the future.

WE RELY ON AIR TRANSPORT TO SHIP PRODUCTS TO OUR CUSTOMERS.

Any disruption in standard air transport systems could have an adverse effect on
our business.


                                       19





WE RELY ON INTERNATIONAL SALES, WHICH ARE SUBJECT TO ADDITIONAL RISKS.

International  sales accounted for  approximately 45% and 40% of our revenues in
the first three months of 2003 and 2002,  respectively.  International sales can
be subject to many inherent  risks that are  difficult or  impossible  for us to
predict or control, including:

o    unexpected changes in regulatory requirements and tariffs;

o    difficulties  and costs  associated  with in staffing and managing  foreign
     operations, including foreign distributor relationships;

o    longer accounts receivable collection cycles in certain foreign countries;

o    adverse economic or political changes;

o    unexpected changes in regulatory requirements;

o    more limited protection for intellectual property in some countries;

o    changes in our international distribution network and direct sales force;

o    potential  trade  restrictions,  exchange  controls  and  import and export
     licensing requirements;

o    problems in collecting accounts receivable;

o    potentially adverse tax consequences of overlapping tax structure; and

o    impairment of the ability to transport goods internationally.

We intend to continue to generate  revenues  from sales outside North America in
the future.  Future  distribution of our products outside North America also may
be subject to greater governmental regulation. These regulations,  which include
requirements for approvals or clearance to market,  additional time required for
regulatory  review and sanctions  imposed for  violations,  as well as the other
risks indicated in the bullets listed above, vary by country. We may not be able
to obtain  regulatory  approvals in the countries in which we currently sell our
products  or in  countries  where we may sell our  products  in the  future.  In
addition,  we may be required to incur significant costs in obtaining  necessary
regulatory  approvals.  Failure to obtain necessary  regulatory approvals or any
other failure to comply with regulatory  requirements could result in a material
reduction in our revenues and earnings.

We also  depend  on  third-party  distributors  for a  material  portion  of our
international sales. If we lose or suffer any significant  reduction in sales to
any material distributor, our business could be materially adversely affected.

In addition,  approximately 34% of our sales in the three months ended March 31,
2003, were made in foreign currencies, primarily the Euro. A significant portion
of the foreign currencies in which we conduct our business is currently,  or may
in the future be,  denominated  in Euros.  We are not  certain  about the future
effect  of  the  Euro  on  our  business,  financial  condition  or  results  of
operations.  In the past,  gains and losses on the  collection  of our  accounts
receivable  arising from  international  operations have contributed to negative
fluctuations in our results of operations. In general, increases in the exchange
rate of the United  States  dollar to foreign  currencies  cause our products to
become  relatively more expensive to customers in those countries,  leading to a
reduction in sales or profitability in some cases. We historically have not, and
currently  are not,  using  hedging  transactions  or other  means to reduce our
exposure to fluctuations in the value of the United States dollar as compared to
the foreign currencies in which many of our sales are made.


                                       20





OUR OPERATING RESULTS MAY FLUCTUATE.

Our operating  results may vary  significantly  from quarter to quarter and from
year to year as a result of a variety of factors. These factors include:

o    level of demand for our products;

o    changes in our customer and product mix;

o    timing of acquisitions and investments in infrastructure;

o    competitive conditions;

o    timing and extent of intellectual property litigation;

o    exchange rate fluctuations; and

o    general economic and political conditions.

We  believe  that  quarterly  comparisons  of  our  financial  results  may  not
necessarily  be  meaningful  and should not be relied upon as an  indication  of
future  performance.  Additionally,  if our  operating  results  in one or  more
quarters do not meet the expectations of security analysts or others,  the price
of our common  stock  could be  materially  adversely  affected.  Our  continued
investment in product  development  and sales and  marketing  are  significantly
ongoing expenses. If revenue in a particular period falls short of expectations,
we may not be able to reduce  significantly  our  expenditures  for that period,
which would materially adversely affect the operating results for that period.

WE MAY BE UNABLE TO PROTECT OUR TRADEMARKS, TRADE SECRETS AND OTHER INTELLECTUAL
PROPERTY RIGHTS THAT ARE IMPORTANT TO OUR BUSINESS.

We regard our  trademarks,  trade secrets and other  intellectual  property as a
component of our success.  We rely on trademark law and trade secret  protection
and  confidentiality  and/or  license  agreements  with  employees,   customers,
partners and others to protect our intellectual  property.  Effective  trademark
and trade secret  protection  may not be available in every country in which our
products are  available.  We cannot be certain that we have taken adequate steps
to protect our intellectual property, especially in countries where the laws may
not  protect  our  rights as fully as in the United  States.  In  addition,  our
third-party  confidentiality  agreements can be breached and, if they are, there
may not be an  adequate  remedy  available  to us. If our trade  secrets  become
known, we may lose our competitive position.

INTELLECTUAL PROPERTY OR OTHER LITIGATION COULD HARM OUR BUSINESS.

Litigation regarding patents and other intellectual property rights is extensive
in the biotechnology  industry. We are aware that patents have been applied for,
and in some  cases  issued to others,  claiming  technologies  that are  closely
related to ours. As a result,  and in part due to the  ambiguities  and evolving
nature  of  intellectual  property  law,  we  periodically  receive  notices  of
potential  infringement  of  patents  held by others.  Although  to date we have
successfully  resolved these types of claims, we may not be able to do so in the
future.

In the event of an intellectual  property dispute, we may be forced to litigate.
This  litigation  could  involve  proceedings  declared  by the U.S.  Patent and
Trademark Office or the International  Trade Commission,  as well as proceedings
brought directly by affected third parties. Intellectual property litigation can
be extremely expensive,  and these expenses,  as well as the consequences should
we not prevail, could seriously harm our business.

If a third party claimed an intellectual property right to technology we use, we
might need to  discontinue  an  important  product or  product  line,  alter our
products  and  processes,  pay  license  fees or  cease  our  affected  business
activities.  Although  we might under  these  circumstances  attempt to obtain a
license to this intellectual  property, we may not be able to do so on favorable
terms,  or at all.


                                       21





In addition to intellectual property litigation,  other substantial,  complex or
extended  litigation could result in large expenditures by us and distraction of
our management. For example, lawsuits by employees, stockholders,  collaborators
or  distributors  could be very costly and  substantially  disrupt our business.
Disputes from time to time with companies or individuals are not uncommon in our
industry,  and we cannot  assure you that we will always be able to resolve them
out of court.

ACCIDENTS RELATED TO HAZARDOUS MATERIALS COULD ADVERSELY AFFECT OUR BUSINESS.

Portions  of  our  operations  require  the  controlled  use  of  hazardous  and
radioactive materials. Although we believe our safety procedures comply with the
standards prescribed by federal, state, local and foreign regulations,  the risk
of  accidental  contamination  of property or injury to  individuals  from these
materials cannot be completely eliminated. In the event of an accident, we could
be liable for any damages that result, which could seriously damage our business
and results of operations.

OUR SALES ARE SUBJECT TO  SEASONALITY,  WHICH MEANS THAT WE HAVE LESS REVENUE IN
SOME MONTHS.

We  experience  a slowing  of sales in  Europe  during  the  summer  months  and
worldwide during the Christmas holidays.  Generally, our fourth quarter revenues
are lower than our revenues in each of the first three  quarters of the year. We
believe  that  period to period  comparisons  of our  operating  results may not
necessarily be reliable indicators of our future performance.  It is likely that
in some future period our operating  results will not meet expectations or those
of public market analysts,  which could result in reductions in the market price
of our common stock.

POTENTIAL  PRODUCT  LIABILITY  CLAIMS COULD  AFFECT OUR  EARNINGS AND  FINANCIAL
CONDITION.

We face a potential risk of liability claims based on our products and services,
and we have faced such claims in the past. We carry product liability  insurance
coverage  which is  limited  in scope  and  amount  but which we  believe  to be
adequate.  We cannot assure you, however,  that we will be able to maintain this
insurance at reasonable cost and on reasonable terms. We also cannot assure that
this insurance will be adequate to protect us against a product liability claim,
should one arise.

THE  LABOR  LAWS  APPLICABLE  TO  OUR  EMPLOYEES  IN  EUROPE  MAY  RESTRICT  THE
FLEXIBILITY OF OUR MANAGEMENT.

As of March 31, 2003,  61 of our 291 employees  worked for our BioSource  Europe
subsidiary,  which is located in Nivelles, Belgium. As a result of Belgian labor
laws,  we are  required  to make  specified  severance  payments in the event we
terminate a European employee. Accordingly, our management may be limited by the
application of the Belgian labor laws in the  determination  of staffing levels,
and may have less flexibility in making such determinations than our competitors
whose employees are not subject to similar labor laws.

                       RISKS ASSOCIATED WITH OUR INDUSTRY

THE BIOMEDICAL  RESEARCH PRODUCTS  INDUSTRY IS VERY  COMPETITIVE,  AND WE MAY BE
UNABLE TO CONTINUE TO COMPETE EFFECTIVELY IN THIS INDUSTRY IN THE FUTURE.

We are engaged in a segment of the biomedical research products industry that is
highly  competitive.  We compete with many other  suppliers and new  competitors
continue  to enter the  markets.  Many of our  competitors,  both in the  United
States and  elsewhere,  are major  pharmaceutical,  chemical  and  biotechnology
companies,  and  many of them  have  substantially  greater  capital  resources,
marketing  experience,  research and development  staffs, and facilities than we
do. Any of these  companies  could succeed in developing  products that are more
effective  than the  products  that we have or may  develop and may also be more
successful  than us in producing and marketing  their  products.  We expect this
competition to continue and intensify in the future.  Competition in our markets
is primarily driven by:

o    product performance, features and liability;

o    price;


                                       22





o    timing of product introductions;

o    ability  to  develop,   maintain  and  protect  proprietary   products  and
     technologies;

o    sales and distribution capabilities;

o    technical support and service;

o    brand royalty;

o    applications support; and

o    breadth of product line.

If a competitor develops superior  technology or cost-effective  alternatives to
our products, our business,  financial condition and results of operations could
be materially adversely affected.

Our  competitors  have in the past and may in the  future  compete  by  lowering
prices.  Our failure to anticipate and respond to price competition could reduce
our revenues and profits, and may damage our market share.

Our industry has also seen substantial  consolidation in recent years, which has
led to the creation of  competitors  with  greater  financial  and  intellectual
property resources than us. In addition, we believe that the success that others
have had in our industry will attract new  competitors.  Some of our current and
future  competitors  also may cooperate to better compete against us. We may not
be able to compete  effectively  against  these  current or future  competitors.
Increased competition could result in price reductions for our products, reduced
margins  and loss of market  share,  any of which  could  adversely  impact  our
business, financial condition and results of operations.

AS A  RESULT  OF  CONSOLIDATION  IN THE  PHARMACEUTICAL  INDUSTRY,  WE MAY  LOSE
EXISTING CUSTOMERS OR HAVE GREATER DIFFICULTY OBTAINING NEW CUSTOMERS.

In recent  years,  the  United  States  pharmaceutical  industry  has  undergone
substantial  consolidation.  As part of many  business  combinations,  companies
frequently  reduce the number of suppliers  used and we may not be selected as a
supplier  after  any  business  combination.   Further,   mergers  or  corporate
consolidations  in the  pharmaceutical  industry could cause us to lose existing
customers and potential  future  customers,  which could have a material adverse
effect on our business, financial condition and results of operations.

WE ARE CURRENTLY SUBJECT TO GOVERNMENT REGULATION.

Our business is currently  subject to regulation,  supervision  and licensing by
federal,  state and local governmental  authorities.  Also, from time to time we
must expend  resources  to comply  with newly  adopted  regulations,  as well as
changes in existing regulations. If we fail to comply with these regulations, we
could be subject to disciplinary actions or administrative  enforcement actions.
These actions could result in penalties, including fines.

                     RISKS ASSOCIATED WITH OUR COMMON STOCK

OUR STOCK PRICE HAS BEEN VOLATILE.

Our common  stock is quoted on the Nasdaq  National  Market,  and there has been
substantial  volatility  in the market  price of our common  stock.  The trading
price of our common stock has been,  and is likely to continue to be, subject to
significant fluctuations due to a variety of factors, including:

o    fluctuations in our quarterly operating and earnings per share results;

o    the gain or loss of significant contracts;


                                       23





o    loss of key personnel;

o    announcements  of  technological  innovations  or new products by us or our
     competitors;

o    delays in the development and introduction of new products;

o    legislative or regulatory changes;

o    general trends in the industry;

o    recommendations  and/or changes in estimates by equity and market  research
     analysts;

o    biological or medical discoveries;

o    disputes and/or developments  concerning  intellectual property,  including
     patents and litigation matters;

o    public concern as to the safety of new technologies;

o    sales of common stock of existing holders;

o    securities class action or other litigation;

o    developments  in our  relationships  with current or future  customers  and
     suppliers; and

o    general economic conditions, both in the United States and abroad.

As a result of these factors,  and  potentially  others,  the sales price of our
common  stock has ranged  from  $2.41 to $32.00 per share from  January 1, 1998,
through March 31, 2003,  and from $5.83 to $6.95 per share from January 1, 2003,
through March 31, 2003.

In  addition,  the stock  market in general has  experienced  extreme  price and
volume  fluctuations that have affected the market price of our common stock, as
well as the stock of many biotechnology companies. Often, price fluctuations are
unrelated to operating  performance  of the  specific  companies  whose stock is
affected.

In the past,  following periods of volatility in the market price of a company's
stock,  securities  class action  litigation  has  occurred  against the issuing
company.  If we were subject to this type of litigation in the future,  we could
incur  substantial  costs and a  diversion  of our  management's  attention  and
resources, each of which could have a material adverse effect on our revenue and
earnings.  Any  adverse  determination  in this type of  litigation  could  also
subject us to significant liabilities.

ANTI-TAKEOVER  PROVISIONS IN OUR GOVERNING  DOCUMENTS AND UNDER  APPLICABLE  LAW
COULD IMPAIR THE ABILITY OF A THIRD PARTY TO TAKE OVER OUR COMPANY.

We are subject to various  legal and  contractual  provisions  that may impede a
change in our control, including the following:

o    our  adoption of a  stockholders'  rights  plan,  which could result in the
     significant  dilution  of the  proportionate  ownership  of any person that
     engages in an unsolicited attempt to take over our company; and

o    the ability of our board of  directors  to issue  additional  shares of our
     preferred stock,  which shares may be given superior  voting,  liquidation,
     distribution and other rights as compared to our common stock.

These   provisions,   as  well  as  other   provisions  in  our  certificate  of
incorporation  and bylaws and under the Delaware General  Corporations  Law, may
make it more  difficult  for a third party to acquire our  company,  even if the
acquisition  attempt was at a premium  over the market value of our common stock
at that time.


                                       24





Our principal  stockholders  and management own a significant  percentage of our
capital  stock  and  will be able to  exercise  significant  influence  over our
affairs.  Our executive  officers,  directors and  principal  stockholders  will
continue to beneficially own 34.5% of our outstanding  common stock,  based upon
the  beneficial  ownership of our common stock as of May 15, 2003.  In addition,
these same persons also hold options to acquire  additional shares of our common
stock, which may increase their percentage ownership of the common stock further
in the future. Accordingly, these stockholders:

o    will be able to  significantly  influence the  composition  of our board of
     directors;

o    will significantly  influence all matters requiring  stockholder  approval,
     including change of control transactions; and

o    will continue to have significant influence over our business.

This  concentration  of  ownership  of our common stock could have the effect of
delaying or  preventing  a change of control of us or otherwise  discouraging  a
potential  acquirer from  attempting to obtain control of us. This in turn could
have a negative  effect on the market price of our common  stock.  It could also
prevent our  stockholders  from  realizing a premium over the market  prices for
their shares of common stock.

OUR PRINCIPAL  STOCKHOLDERS  AND MANAGEMENT OWN A SIGNIFICANT  PERCENTAGE OF OUR
CAPITAL  STOCK  AND  WILL BE ABLE TO  EXERCISE  SIGNIFICANT  INFLUENCE  OVER OUR
AFFAIRS.

Our executive officers,  directors and principal  stockholders  beneficially own
approximately  34.5% of our outstanding  common stock, based upon the beneficial
ownership  of  our  common  stock  as  of  May  15,  2003.  As a  result,  these
stockholders,  if they act  together,  could exert  substantial  influence  over
matters requiring stockholder approval,  including the election of directors and
approval of mergers and other  significant  corporate  transactions.  The voting
power of such persons may have the effect of delaying, preventing or deterring a
change in control, and could affect the market price of our common stock.

ABSENCE OF DIVIDENDS COULD REDUCE OUR ATTRACTIVENESS TO YOU.

Some  investors  favor  companies that pay  dividends,  particularly  in general
downturns in the stock market. We have never declared or paid any cash dividends
on our common  stock.  We  currently  intend to retain any future  earnings  for
funding growth and we do not currently  anticipate  paying cash dividends on our
common stock in the foreseeable  future.  Because we may not pay dividends,  the
return on this investment likely depends on selling this stock at a profit.


ITEM 3. QUANTITATIVE AND QUALITATIVE DISCLOSURES OF MARKET RISK

We conduct business in various foreign  currencies and are therefore  subject to
the  transaction  exposures  that arise from  foreign  exchange  rate  movements
between the dates that foreign currency  transactions are initiated and the date
that they are converted.  We are also subject to certain  exposures arising from
the  translation  and  consolidation  of the  financial  results of our  foreign
subsidiaries.  There can be no  assurance  that  actions  taken to  manage  such
exposures  will  continue to be  successful  or that future  changes in currency
exchange  rates will not have a material  impact on our future cash  collections
and operating results.  We do not currently hedge either our transaction risk or
our economic risk.


ITEM 4. CONTROLS AND PROCEDURES


EVALUATION OF CONTROLS AND PROCEDURES


Within 90 days prior to the  filing of this  report,  members  of the  Company's
management,  including the Company's President and Chief Executive Officer,  Len
Hendrickson,   and  Chief  Financial  Officer,   Charles  Best,   evaluated  the
effectiveness of the design and operation of the Company's  disclosure  controls
and procedures. Based upon that


                                       25





evaluation,  Mr.  Hendrickson  and Mr. Best believe  that, as of the date of the
evaluation,  the Company's  disclosure  controls and procedures are effective in
making known to them material information relating to the Company (including its
consolidated subsidiaries) required to be included in this report.


Disclosure controls and procedures, no matter how well designed and implemented,
can provide  only  reasonable  assurance  of  achieving  an entity's  disclosure
objectives.   The  likelihood  of  achieving  such  objectives  is  affected  by
limitations  inherent in disclosure  controls and procedures.  These include the
fact that human judgment in decision-making can be faulty and that breakdowns in
internal  control can occur  because of human  failures such as simple errors or
mistakes or intentional circumvention of the established process.

There were no significant changes in the Company's internal controls or in other
factors that could  significantly  affect these  internal  controls known to Mr.
Hendrickson or to Mr. Best after the date of the most recent evaluation.


                                       26






                                     PART II

                                OTHER INFORMATION

ITEM 1.  LEGAL PROCEEDINGS
         None

ITEM 2.  CHANGE IN SECURITIES AND USE OF PROCEEDS
         None

ITEM 3.  DEFAULTS UPON SENIOR SECURITIES
         None.

ITEM 4.  SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS.
         None

ITEM 5.  OTHER INFORMATION
         None.

ITEM 6.  EXHIBITS AND REPORTS ON FORM 8-K

         (a) Exhibits
                Exhibit 99.1    Certificate of our Chief  Executive  Officer and
                                Chief Financial Officer  pursuant to Section 906
                                of the Sarbanes-Oxley Act of 2002.

         (b) Reports on Form 8-K

                  The Company filed a Current Report on Form 8-K on February 21,
                  2003, reporting the issuance of a press release announcing the
                  Company's  financial  results for the fiscal  quarter and year
                  ended December 31, 2002.


                                       27





                                   SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, as amended,
the  registrant  has duly  caused  this report to be signed on its behalf by the
undersigned thereunto duly authorized.




                                           BIOSOURCE INTERNATIONAL, INC.
                                                         (Registrant)




Date:  May 12, 2003                          /s/ LEONARD M. HENDRICKSON
                                             --------------------------
                                                Leonard M. Hendrickson
                                                President and
                                                Chief Executive Officer




Date:  May 12, 2003                          /s/ CHARLES C. BEST
                                             -------------------
                                                Charles C. Best
                                                Executive Vice President and
                                                Chief Financial Officer


                                       28





                        Certification of CEO Pursuant to
                 Securities Exchange Act Rules 13a-14 and 15d-14
                             as Adopted Pursuant to
                  Section 302 of the Sarbanes-Oxley Act of 2002


I, Leonard M. Hendrickson certify that:

         1. I have  reviewed  this  quarterly  report on Form 10-Q for the three
months ended March 31, 2003;

         2. Based on my knowledge,  this  quarterly  report does not contain any
untrue  statement of a material fact or omit to state a material fact  necessary
to make the  statements  made,  in light of the  circumstances  under which such
statements  were made, not misleading with respect to the period covered by this
quarterly report;

         3. Based on my knowledge, the financial statements, and other financial
information  included in this quarterly  report,  fairly present in all material
respects the financial  condition,  results of operations  and cash flows of the
registrant as of, and for, the periods presented in this quarterly report;

         4. The registrant's other certifying officers and I are responsible for
establishing and maintaining  disclosure  controls and procedures (as defined in
Exchange Act Rules 13a-14 and 15d-14) for the registrant and we have:

                  a) designed such disclosure  controls and procedures to ensure
that material information relating to the registrant, including its consolidated
subsidiaries, is made known to us by others within those entities,  particularly
during the period in which this quarterly report is being prepared;

                  b) evaluated the effectiveness of the registrant's  disclosure
controls and  procedures as of a date within 90 days prior to the filing date of
this quarterly report (the "Evaluation Date"); and

                  c) presented in this quarterly  report our  conclusions  about
the  effectiveness  of the  disclosure  controls  and  procedures  based  on our
evaluation as of the Evaluation Date;

         5. The  registrant's  other  certifying  officers and I have disclosed,
based on our most recent evaluation,  to the registrant's auditors and the audit
committee  of  registrant's  board  of  directors  (or  persons  performing  the
equivalent function):

                  a) all significant  deficiencies in the design or operation of
internal  controls  which could  adversely  affect the  registrant's  ability to
record, process, summarize and report financial data and have identified for the
registrant's auditors any material weaknesses in internal controls; and

                  b)  any  fraud,   whether  or  not  material,   that  involves
management or other  employees who have a significant  role in the  registrant's
internal controls; and

         6. The registrant's  other certifying  officers and I have indicated in
this quarterly report whether or not there were significant  changes in internal
controls or in other factors that could  significantly  affect internal controls
subsequent to the date of our most recent  evaluation,  including any corrective
actions with regard to significant deficiencies and material weaknesses.

Date: May 12, 2003
                                           /s/LEONARD M. HENDRICKSON
                                           -------------------------------------
                                           Leonard M. Hendrickson
                                           President and Chief Executive Officer


                                       29





                        Certification of CFO Pursuant to
                 Securities Exchange Act Rules 13a-14 and 15d-14
                             as Adopted Pursuant to
                  Section 302 of the Sarbanes-Oxley Act of 2002


I, Charles C. Best certify that:

         1. I have  reviewed  this  quarterly  report on Form 10-Q for the three
months ended March 31, 2003;

         2. Based on my knowledge,  this  quarterly  report does not contain any
untrue  statement of a material fact or omit to state a material fact  necessary
to make the  statements  made,  in light of the  circumstances  under which such
statements  were made, not misleading with respect to the period covered by this
quarterly report;

         3. Based on my knowledge, the financial statements, and other financial
information  included in this quarterly  report,  fairly present in all material
respects the financial  condition,  results of operations  and cash flows of the
registrant as of, and for, the periods presented in this quarterly report;

         4. The registrant's other certifying officers and I are responsible for
establishing and maintaining  disclosure  controls and procedures (as defined in
Exchange Act Rules 13a-14 and 15d-14) for the registrant and we have:

                  a) designed such disclosure  controls and procedures to ensure
that material information relating to the registrant, including its consolidated
subsidiaries, is made known to us by others within those entities,  particularly
during the period in which this quarterly report is being prepared;

                  b) evaluated the effectiveness of the registrant's  disclosure
controls and  procedures as of a date within 90 days prior to the filing date of
this quarterly report (the "Evaluation Date"); and

                  c) presented in this quarterly  report our  conclusions  about
the  effectiveness  of the  disclosure  controls  and  procedures  based  on our
evaluation as of the Evaluation Date;

         5. The  registrant's  other  certifying  officers and I have disclosed,
based on our most recent evaluation,  to the registrant's auditors and the audit
committee  of  registrant's  board  of  directors  (or  persons  performing  the
equivalent function):

                  a) all significant  deficiencies in the design or operation of
internal  controls  which could  adversely  affect the  registrant's  ability to
record, process, summarize and report financial data and have identified for the
registrant's auditors any material weaknesses in internal controls; and

                  b)  any  fraud,   whether  or  not  material,   that  involves
management or other  employees who have a significant  role in the  registrant's
internal controls; and

         6. The registrant's  other certifying  officers and I have indicated in
this quarterly report whether or not there were significant  changes in internal
controls or in other factors that could  significantly  affect internal controls
subsequent to the date of our most recent  evaluation,  including any corrective
actions with regard to significant deficiencies and material weaknesses.

Date: May 12, 2003
                                           /s/ CHARLES C. BEST
                                           -------------------------------------
                                           Charles C. Best
                                           Chief Financial Officer


                                       30





                                  EXHIBIT INDEX

Exhibit           Description
- -------           -----------

99.1              Certificate of our Chief Executive Officer and Chief Financial
                  Officer pursuant to Section 906 of the  Sarbanes-Oxley  Act of
                  2002.


                                       31