EXHIBIT 10.1

                         EXECUTIVE EMPLOYMENT AGREEMENT

         This Executive  Employment  Agreement  (this  "AGREEMENT")  is made and
entered into as of this 15th day of  February,  2004,  by and between  BioSource
International,  Inc., a Delaware corporation (the "COMPANY") and Kevin J. Reagan
("EXECUTIVE").

         1.       ENGAGEMENT AND DUTIES.

                  1.1      Commencing  upon February 15th,  2004 (the "EFFECTIVE
DATE"),  and upon the  terms and  subject  to the  conditions  set forth in this
Agreement, the Company hereby engages and employs Executive as an officer of the
Company,  with the title and  designation of Executive Vice  President-Technical
Operations  of  the  Company.  Executive  hereby  accepts  such  engagement  and
employment.

                  1.2      Executive's  duties  and  responsibilities  shall  be
those  normally  and  customarily   vested  in  the  office  of  Executive  Vice
President-Technical  Operations of a  corporation,  subject to the  supervision,
direction and control of the President of the Company.  Specifically,  Executive
is responsible  for the Company's R&D  operations in Foster City,  Hopkinton and
Camarillo,  the Company's manufacturing  operations in Camarillo,  the Company's
global  quality  operations  and a dotted  line  responsibility  for the R&D and
manufacturing  operations in BioSource Europe. In addition,  Executive's  duties
shall  include  those duties and services for the Company and its  affiliates as
the President shall from time to time reasonably direct.  Executive shall report
directly to the President.

                  1.3      Executive agrees to devote his primary business time,
energies,  skills, efforts and attention to his duties hereunder,  and will not,
without the prior  written  consent of the  Company,  which  consent will not be
unreasonably  withheld,  render  any  material  services  to any other  business
concern.  Executive  will use his best  efforts  and  abilities  faithfully  and
diligently to promote the Company's business interests.

                  1.4      Except for routine travel incident to the business of
the  Company,  Executive  shall  perform his duties and  obligations  under this
Agreement  principally  from an office  provided  by the  Company in  Camarillo,
California,  or such  other  location,  as the  President  may from time to time
determine.

         2.       TERM OF EMPLOYMENT.  Executive's  employment  pursuant to this
Agreement  shall  commence  on the  Effective  Date and shall  terminate  on the
earliest to occur of the following:

                  (a)      the close of business on December 31, 2007;

                  (b)      the death of Executive;

                  (c)      delivery   to   Executive   of   written   notice  of
termination by the Company if Executive  shall suffer a "permanent  disability,"
which for purposes of this Agreement shall mean a physical or mental  disability
which,  in the  reasonable  judgment  of the  President,  is  likely  to  render
Executive unable to perform his duties and obligations  under this Agreement for
90 days in any 12-month period;

                  (d)      delivery   to   Executive   of   written   notice  of
termination  by the Company  "for  cause," by reason of: (i) any act or omission
knowingly  undertaken or omitted by Executive  with the intent of causing damage
to the  Company,  its  properties,  assets  or  business  or  its  stockholders,
officers, directors or employees; (ii) any act of Executive involving a material


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personal  profit  to  Executive,   including,  without  limitation,  any  fraud,
misappropriation or embezzlement,  involving properties,  assets or funds of the
Company or any of its  subsidiaries;  (iii)  Executive's  consistent  failure to
perform  his  normal  duties  or any  obligation  under  any  provision  of this
Agreement, in either case, as directed by the President;  (iv) conviction of, or
pleading nolo contendere to, (A) any crime or offense  involving monies or other
property  of the  Company;  (B) any  felony  offense;  or (C) any crime of moral
turpitude;  or (v) the  chronic  or  habitual  use or  consumption  of  drugs or
alcoholic beverages; or

                  (e)      delivery   to   Executive   of   written   notice  of
termination by the Company "without cause."

         3.       COMPENSATION; EXECUTIVE BENEFIT PLANS.

                  3.1      The Company  shall pay to  Executive a base salary at
an annual rate of $190,000 during each fiscal year of this Agreement, subject to
adjustment on an annual basis by the President. The base salary shall be payable
in installments throughout the year in the same manner and at the same times the
Company pays base salaries to other  executive  officers of the Company.  In the
event that Executive's employment is terminated pursuant to SECTION 2(E), above,
the Company shall  continue to pay  Executive's  then-current  base salary for a
period  of 9  months  following  the  effective  date of such  termination,  and
Executive shall retain only those options  described in SECTION 3.4, below, that
have vested prior to the effective date of such termination. Notwithstanding the
foregoing,  the Company  shall not be  obligated  to pay  Executive  any amounts
hereunder  following  the  termination  of  Executive's  employment  pursuant to
SECTION  2(E),  above,  from  and  after  any time  that  Executive  accepts  an
employment or  consulting  position with any person or entity that is determined
by  the  President,  in  the  exercise  of his  reasonable  discretion,  to be a
competitor of the Company.

                  3.2      In  addition  to  the  Base  Salary  to  be  paid  to
Executive  hereunder,  the Company shall pay a  performance  bonus (the "BONUS")
determined  in  accordance  with a management  incentive  plan (the "MIP") to be
approved in a resolution adopted by the Compensation  Committee.  The management
incentive  plan will  provide for the payment of an annual Bonus equal to 30% of
the then current base salary upon achieving the "target" objectives set forth in
the MIP, and payments of such lesser or greater  amounts upon achieving  results
less than or greater than the "target"  objectives  as shall be contained in the
MIP.

                  3.3      Executive  shall be  granted  an option  to  purchase
30,000 shares of Common Stock at a per share  exercise  price equal to the "fair
market value" of such shares on the Effective  Date (as defined in the Company's
2000 Stock  Incentive  Plan (the "STOCK  PLAN")).  The  Options  shall be issued
pursuant to the terms of the Stock Plan, and shall vest as to 25% of the Options
on the first anniversary of the date of grant, and as to 1/48th of the Option on
the last day of each calendar month  thereafter  until fully vested.  The option
agreement  will  provide for the  acceleration  of all vesting  upon a change of
control,  as  defined  in  the  option  agreement,  that  occurs  prior  to  the
termination of this  Agreement.  In addition,  all previous grants of options to
the Executive  shall be modified so that such options shall also  accelerate and
become fully vested upon a change of control.

                  3.4      Executive shall be entitled to reimbursement from the
Company for the reasonable costs and expenses which he incurs in connection with
the performance of his duties and  obligations  under this Agreement in a manner
consistent with the Company's practices and policies as adopted or approved from
time to time by the President for executive officers.


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                  3.5      The Company may deduct from any compensation  payable
to Executive the minimum amounts sufficient to cover applicable  federal,  state
and/or local income tax  withholding,  old-age and  survivors'  and other social
security payments, state disability and other insurance premiums and payments.

         4.       OTHER BENEFITS.  During the term of his employment  hereunder,
Executive shall be eligible to participate in all operative employee benefit and
welfare  plans of the Company then in effect from time to time and in respect of
which  all  executive   officers  of  the  Company  generally  are  entitled  to
participate ("COMPANY EXECUTIVE BENEFIT PLANS"),  including,  to the extent then
in effect, group life, medical, disability and other insurance plans, all on the
same basis  applicable to employees of the Company whose level of management and
authority is comparable to that of Executive.

         5.       CONFIDENTIALITY OF PROPRIETARY INFORMATION AND MATERIAL.

                  5.1      INDUSTRIAL  PROPERTY RIGHTS.  For the purpose of this
Agreement, "INDUSTRIAL PROPERTY RIGHTS" shall mean all of the Company's patents,
trademarks,  trade names,  inventions,  copyrights,  know-how or trade  secrets,
formulas and science, now in existence or hereafter developed or acquired by the
Company or for its use,  relating to any and all products and services which are
developed, formulated and/or manufactured by the Company.

                  5.2      TRADE  SECRETS.  For the  purpose of this  Agreement,
"TRADE  SECRETS"  shall mean any formula,  pattern,  device,  or  compilation of
information  that is used in the  Company's  business  and gives the  Company an
opportunity to obtain an advantage over its  competitors  who do not know and/or
do not use it. This term includes,  but is not limited to, information  relating
to the marketing of the Company's products and services,  including price lists,
pricing  information,  customer lists,  customer names,  the particular needs of
customers,  information  relating to their desirability as customers,  financial
information,  intangible property and other such information which is not in the
public domain.

                  5.3      TECHNICAL  DATA.  For the purpose of this  Agreement,
"TECHNICAL  DATA" shall mean all information of the Company in written,  graphic
or  tangible  form  relating  to any  and  all  products  which  are  developed,
formulated and/or  manufactured by the Company, as such information exists as of
the Effective Date or is developed by the Company during the term hereof.

                  5.4      PROPRIETARY  INFORMATION.  For  the  purpose  of this
Agreement,  "PROPRIETARY INFORMATION" shall mean all of the Company's Industrial
Property Rights, Trade Secrets and Technical Data. Proprietary Information shall
not  include  any  information  which  (i) was  lawfully  in the  possession  of
Executive prior to Executive's employment with the Company, (ii) may be obtained
by a  reasonably  diligent  businessperson  from  readily  available  and public
sources  of  information,   (iii)  is  lawfully  disclosed  to  Executive  after
termination  of  Executive's  employment by a third party which does not have an
obligation  to the  Company to keep such  information  confidential,  or (iv) is
independently developed by Executive after termination of Executive's employment
without utilizing any of the Company's Proprietary Information.


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                  5.5      AGREEMENT NOT TO COPY OR USE.  Executive  agrees,  at
any time  during  the term of his  employment  and for a  period  of five  years
thereafter,  not to copy, use or disclose (except as required by law after first
notifying the Company and giving it an  opportunity  to object) any  Proprietary
Information  without the  Company's  prior written  permission.  The Company may
withhold such permission as a matter within its sole discretion  during the term
of this Agreement and thereafter.

         6.       RETURN  OF  CORPORATE  PROPERTY  AND TRADE  SECRETS.  Upon any
termination  of this  Agreement,  Executive  shall turn over to the  Company all
property,  writings or documents then in his possession or custody  belonging to
or  relating  to the  affairs of the  Company or  comprising  or relating to any
Proprietary Information.

         7.       DISCOVERIES AND INVENTIONS.

                  7.1      DISCLOSURE.   Executive  will  promptly  disclose  in
writing to the Company complete information concerning each and every invention,
discovery,  improvement,  device, design, apparatus,  practice, process, method,
product or work of  authorship,  whether  patentable  or not,  made,  developed,
perfected, devised, conceived or first reduced to practice by Executive, whether
or not during regular working hours (hereinafter referred to as "Developments"),
either  solely or in  collaboration  with others,  (a) prior to the term of this
Agreement  while working for the Company,  (b) during the term of this Agreement
or (c) within six months after the term of this  Agreement,  if relating  either
directly or  indirectly  to the  business,  products,  practices,  techniques or
confidential information of the Company.

                  7.2      ASSIGNMENT.  Executive, to the extent that he has the
legal right to do so, hereby  acknowledges that any and all Developments are the
property of the  Company and hereby  assigns and agrees to assign to the Company
any and all of  Executive's  right,  title and interest in and to any and all of
such Developments;  PROVIDED, HOWEVER, that, in accordance with California Labor
Code Sections 2870 and 2872,  the provisions of this SECTION 7.2 shall not apply
to any Development that the Executive developed entirely on his own time without
using the Company's equipment,  supplies, facilities or trade secret information
except for those Developments that either:

                           (a)      relate   at  the  time  of   conception   or
reduction to practice of the Development to the Company's business, or actual or
demonstrably anticipated research or development of the Company; or

                           (b)      result from any work  performed by Executive
for the Company.

                  7.3      ASSISTANCE  OF  EXECUTIVE.  Upon  request and without
further  compensation  therefore,  but at no expense to  Executive,  and whether
during  the  term  of  this  Agreement  or  thereafter,  Executive  will  do all
reasonable lawful acts,  including,  but not limited to, the execution of papers
and lawful oaths and the giving of testimony, that, in the reasonable opinion of
the  Company,  its  successors  and  assigns,  may be  necessary or desirable in
obtaining,  sustaining,  reissuing,  extending and  enforcing  United States and
foreign Letters Patent,  including,  but not limited to, design patents,  on any
and all Developments  and for perfecting,  affirming and recording the Company's
complete  ownership  and title  thereto,  subject to the  proviso in SECTION 7.2
hereof, and Executive will otherwise reasonably cooperate in all proceedings and
matters relating thereto.


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                  7.4      RECORDS.  Executive  will keep  complete and accurate
accounts,  notes,  data and records of all  Developments  in the manner and form
requested by the Company.  Such accounts,  notes,  data and records shall be the
property of the Company, subject to the proviso in SECTION 7.2 hereof, and, upon
request by the Company,  Executive will promptly surrender the same to it or, if
not  previously  surrendered  upon its  request  or  otherwise,  Executive  will
surrender the same, and all copies  thereof,  to the Company upon the conclusion
of his employment.

                  7.5      OBLIGATIONS,  RESTRICTIONS AND LIMITATIONS. Executive
understands  that the Company may enter into  agreements  or  arrangements  with
agencies of the United States  Government and that the Company may be subject to
laws and regulations which impose  obligations,  restrictions and limitations on
it with respect to  inventions  and patents which may be acquired by it or which
may be  conceived  or  developed  by  employees,  consultants  or  other  agents
rendering  services to it.  Executive  agrees that he shall be bound by all such
obligations,  restrictions  and  limitations  applicable  to any such  invention
conceived or developed by him during the term of this  Agreement  and shall take
any and all further action which may be required to discharge  such  obligations
and to comply with such restrictions and limitations.

         8.       NON-SOLICITATION COVENANT.

                  8.1      NONSOLICITATION AND NONINTERFERENCE.  During the term
of this Agreement and for a period of two years thereafter,  Executive shall not
(a) induce or attempt to induce any  employee of the Company to leave the employ
of the Company or in any way interfere  adversely with the relationship  between
any such employee and the Company,  (b) induce or attempt to induce any employee
of the  Company to work for,  render  services  or  provide  advice to or supply
confidential  business  information or trade secrets of the Company to any third
person,  firm or  corporation  or (c) induce or attempt to induce any  customer,
supplier,  licensee, licensor or other business relation of the Company to cease
doing  business with the Company or in any way interfere  with the  relationship
between  any such  customer,  supplier,  licensee,  licensor  or other  business
relation and the Company.

                  8.2      INDIRECT SOLICITATION.  Executive agrees that, during
the term of this Agreement and the period covered by SECTION 8.1 hereof, he will
not,  directly or  indirectly,  assist or encourage any other person in carrying
out,  directly or  indirectly,  any  activity  that would be  prohibited  by the
provisions of SECTION 8.1 if such activity were carried out by Executive, either
directly or indirectly;  and, in particular,  Executive agrees that he will not,
directly  or  indirectly,  induce  any  employee  of the  Company  to carry out,
directly or indirectly, any such activity.

         9.       INJUNCTIVE RELIEF.  Executive hereby recognizes,  acknowledges
and agrees that in the event of any breach by Executive of any of his covenants,
agreements,  duties or  obligations  contained in SECTIONS 5, 6, 7 AND 8 of this
Agreement,  the Company  would suffer  great and  irreparable  harm,  injury and
damage,  the Company would encounter  extreme  difficulty in attempting to prove
the actual amount of damages suffered by the Company as a result of such breach,
and the Company would not be reasonably or adequately  compensated in damages in
any action at law. Executive therefore covenants and agrees that, in addition to
any  other  remedy  the  Company  may have at law,  in  equity,  by  statute  or
otherwise,  in the event of any  breach by  Executive  of any of his  covenants,
agreements,  duties or  obligations  contained in SECTIONS 5, 6, 7 AND 8 of this
Agreement,  the  Company  shall  be  entitled  to seek  and  receive  temporary,
preliminary and permanent  injunctive and other equitable  relief from any court
of competent jurisdiction to enforce any of the rights of the Company, or any of
the covenants,  agreements, duties or obligations of Executive hereunder, and/or
otherwise to prevent the violation of any of the terms or provisions hereof, all
without the  necessity of proving the amount


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of  any  actual  damage  to  the  Company  or any  affiliate  thereof  resulting
therefrom;  provided, however, that nothing contained in this SECTION 9 shall be
deemed or construed in any manner  whatsoever  as a waiver by the Company of any
of the rights which the Company may have against Executive at law, in equity, by
statute or otherwise  arising out of, in connection  with or resulting  from the
breach by Executive of any of his covenants,  agreements,  duties or obligations
hereunder.

         10.      MISCELLANEOUS.

                  10.1     ARBITRATION.  The  parties  agree  that they will use
their best efforts to amicably resolve any dispute arising out of or relating to
this  Agreement.  Any  controversy,  claim or dispute that cannot be so resolved
shall be settled by final binding  arbitration  in accordance  with the rules of
the American Arbitration Association and judgment upon the award rendered by the
arbitrator  or  arbitrators  may be  entered  in any court  having  jurisdiction
thereof.  Any such  arbitration  shall be  conducted  in Los  Angeles  County or
Ventura County,  California,  or such other place as may be mutually agreed upon
by  the  parties.  Within  fifteen  (15)  days  after  the  commencement  of the
arbitration,  each party shall select one person to act arbitrator,  and the two
arbitrators so selected shall select a third arbitrator  within ten (10) days of
their appointment. Each party shall bear its own costs and expenses and an equal
share of the arbitrator's expenses and administrative fees of arbitration.

                  10.2     NOTICES.    All    notices,    requests   and   other
communications (collectively,  "NOTICES") given pursuant to this Agreement shall
be in writing,  and shall be delivered by personal  service or by United  States
first class,  registered or certified mail (return receipt  requested),  postage
prepaid, addressed to the party at the address set forth below:

                           If to Company:

                                    BioSource International, Inc.
                                    542 Flynn Road
                                    Camarillo, CA 93012
                                    Attn: President

                           If  to  Executive,  at  the  address  maintained  for
Executive in the Company's payroll records.

                  Any Notice  shall be deemed  duly given when  received  by the
addressee thereof, provided that any Notice sent by registered or certified mail
shall be deemed to have been duly  given  three days from date of deposit in the
United States mails, unless sooner received.  Either party may from time to time
change its address for further  Notices  hereunder by giving notice to the other
party in the manner prescribed in this section.

                  10.3     ENTIRE  AGREEMENT.  This Agreement  contains the sole
and entire agreement and understanding of the parties with respect to the entire
subject matter of this Agreement, and any and all prior agreements, discussions,
negotiations, commitments and understandings, whether oral or otherwise, related
to  the  subject  matter  of  this  Agreement  are  hereby  merged  herein.   No
representations,  oral or  otherwise,  express  or  implied,  other  than  those
contained  in  this  Agreement  have  been  relied  upon  by any  party  to this
Agreement.

                  10.4     ATTORNEYS'  FEES.  If  any  action,   suit  or  other
proceeding is  instituted to remedy,  prevent or obtain relief from a default in
the  performance  by any party of its  obligations  under  this  Agreement,  the
prevailing  party  shall  recover  all of  such  party's  costs  and  reasonable


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attorneys'  fees  incurred  in  each  and  every  such  action,  suit  or  other
proceeding, including any and all appeals or petitions there from.

                  10.5     GOVERNING  LAW. THIS  AGREEMENT  SHALL BE GOVERNED BY
AND CONSTRUED IN ACCORDANCE  WITH THE LAWS OF THE STATE OF  CALIFORNIA,  WITHOUT
REGARD TO CONFLICTS OF LAW PRINCIPLES THEREOF.

                  10.6     CAPTIONS.  The various captions of this Agreement are
for  reference  only and shall not be  considered  or referred  to in  resolving
questions of interpretation of this Agreement.

                  10.7     COUNTERPARTS.  This  Agreement may be executed in any
number of counterparts, each of which shall be deemed to be an original, but all
of which together shall constitute one and the same instrument.

                  10.8     BUSINESS  DAY.  If  the  last  day   permissible  for
delivery  of any  Notice  under  any  provision  of this  Agreement,  or for the
performance  of any  obligation  under  this  Agreement,  shall be other  than a
business day, such last day for such Notice or performance  shall be extended to
the next following business day (provided, however, under no circumstances shall
this  provision  be  construed  to  extend  the  date  of  termination  of  this
Agreement).

         In witness whereof,  the parties have executed this Agreement as of the
date first set forth above.

Company:                                         Executive:

BIOSOURCE INTERNATIONAL, INC.                    KEVIN J. REAGAN



By: /s/ Terrance J. Bieker                       By: /s/ Kevin J. Reagan
   ----------------------------                      --------------------------
   Terrance J. Bieker, President and CEO


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