UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                   FORM N-CSR


   CERTIFIED SHAREHOLDER REPORT OF REGISTERED MANAGEMENT INVESTMENT COMPANIES

                  Investment Company Act file number 811-4757

                        SMITH BARNEY SECTOR SERIES INC.
               (Exact name of registrant as specified in charter)

                      125 Broad Street, New York, NY 10004
               (Address of principal executive offices) (Zip code)

                            Christina T. Sydor, Esq.
                            300 First Stamford Place
                               Stamford, CT 06902
                     (Name and address of agent for service)

              Registrant's telephone number, including area code:

                                 (800) 451-2010

                      Date of fiscal year end: October 31
                    Date of reporting period: April 30, 2003


ITEM 1.  REPORT TO STOCKHOLDERS.

         The SEMI-ANNUAL Report to Stockholders is filed herewith.




                                  SMITH BARNEY
                               SECTOR SERIES INC.


                                  SMITH BARNEY
                               BIOTECHNOLOGY FUND

              Research Series | Semi-annual Report | April 30, 2003








                        [SMITH BARNEY MUTUAL FUNDS LOGO]


                 YOUR SERIOUS MONEY. PROFESSIONALLY MANAGED(R)


 YOUR SERIOUS MONEY. PROFESSIONALLY MANAGED.(R) is a registered service mark of
                         Citigroup Global Markets Inc.


          NOT FDIC INSURED  o  NOT BANK GUARANTEED  o  MAY LOSE VALUE




[GRAPHIC OMITTED] Research Series

Semi-Annual Report  o  April 30, 2003

SMITH BARNEY BIOTECHNOLOGY FUND

SMITH BARNEY FUND MANAGEMENT LLC

Smith Barney Fund Management LLC is the investment manager to the Fund.
Citigroup Asset Management Ltd. is the subadviser. The Fund's management team
follows a systematic and rigorous approach designed to provide appropriate
exposure to the market sector.

FUND OBJECTIVE*

The Fund seeks long-term capital appreciation. The Fund normally invests at
least 80% of its assets in securities of companies principally engaged in, but
not limited to, the research, development, application, manufacture and
distribution of various biotechnological and biomedical products, services,
processes and related technologies.

FUND FACTS

FUND INCEPTION
- ----------------------
August 31, 2000

WHAT'S INSIDE

Schedule of Investments .....................................................  1
Statement of Assets and Liabilities .........................................  3
Statement of Operations .....................................................  4
Statements of Changes in Net Assets .........................................  5
Notes to Financial Statements ...............................................  6
Financial Highlights ........................................................ 10
Additional Shareholder Information .......................................... 12


- ----------
*    Since the Fund focuses its investments on companies involved in the
     biotechnology industries, an investment in the Fund may involve a greater
     degree of risk than an investment in other mutual funds with greater
     diversification.

[LOGO OMITTED]
SMITH BARNEY MUTUAL FUNDS

YOUR SERIOUS MONEY. PROFESSIONALLY MANAGED(R)

YOUR SERIOUS MONEY. PROFESSIONALLY MANAGED.(R) is a registered service mark of
Citigroup Global Markets Inc.

Investment Products: Not Fdic Insured  o  Not Bank Guaranteed  o  May Lose Value



SCHEDULE OF INVESTMENTS (UNAUDITED)                               APRIL 30, 2003




     SHARES                                SECURITY                                VALUE
=============================================================================================
                                                                       
COMMON STOCK -- 84.8%

BIOTECHNOLOGY -- 62.8%
         17,295     Alkermes, Inc.*                                             $   172,604
         58,544     Amgen Inc.*                                                   3,589,330
                    Applera Corp.:
          7,063      Applied Biosystems Group                                       123,814
          5,893      Celera Genomics Group*                                          61,877
         13,792     Biogen Inc.*                                                    523,958
          4,911     Cell Genesys, Inc.*                                              43,806
          3,355     Charles River Laboratories International, Inc.*                  91,088
         15,614     Chiron Corp.*                                                   637,520
         19,429     Genentech, Inc.*                                                738,108
         34,046     Genzyme Corp.*                                                1,371,373
         17,011     IDEC Pharmaceuticals Corp.*                                     557,110
         13,405     Immunex Corp.*                                                   52,682
          2,966     Invitrogen Corp.*                                                96,988
          5,509     Laboratory Corp. of America Holdings*                           162,295
         12,950     Medarex, Inc.*                                                   54,002
         21,740     MedImmune, Inc.*                                                766,770
         10,484     Millennium Pharmaceuticals, Inc.*                               115,324
          6,844     Monsanto Co.                                                    119,086
         11,541     Neurocrine Biosciences, Inc.*                                   522,230
          6,346     Protein Design Labs, Inc.*                                       63,016
          3,675     Techne Corp.*                                                    81,622
          7,866     Vertex Pharmaceuticals Inc.*                                     94,943
         43,499     XOMA Ltd.*                                                      216,625
- ---------------------------------------------------------------------------------------------
                                                                                 10,256,171
- ---------------------------------------------------------------------------------------------

HEATHCARE EQUIPMENT AND SUPPLIES -- 1.3%
         11,928     Affymetrix, Inc.*                                               221,264
- ---------------------------------------------------------------------------------------------

MEDICAL LABS AND TESTING SERVICES -- 0.8%
          2,065     Quest Diagnostics Inc.*                                         123,384
- ---------------------------------------------------------------------------------------------

PHARMACEUTICALS -- 19.9%
         14,877     Abgenix, Inc.*                                                  141,332
          3,029     Celgene Corp.*                                                   80,602
          9,079     Cubist Pharmaceuticals, Inc.*                                    83,799
          7,092     CV Therapeutics, Inc.*                                          141,698
          4,842     Enzon, Inc.*                                                     66,432
         39,427     Gilead Sciences, Inc.*                                        1,819,162
          8,746     Human Genome Sciences, Inc.*                                    102,241
         23,862     ICOS Corp.*                                                     638,309
          4,747     Osi Pharmaceuticals, Inc.*                                       99,687
          1,659     Trimeris Inc.*                                                   73,643
- ---------------------------------------------------------------------------------------------
                                                                                  3,246,905
- ---------------------------------------------------------------------------------------------

                    TOTAL COMMON STOCK
                    (Cost-- $15,469,620)                                         13,847,724
=============================================================================================



                       SEE NOTES TO FINANCIAL STATEMENTS.

  1  SMITH BARNEY SECTOR SERIES INC. | 2003 Semi-Annual Report to Shareholders


SCHEDULE OF INVESTMENTS (UNAUDITED)(CONTINUED)                    APRIL 30, 2003




      FACE
     AMOUNT                                SECURITY                                VALUE
=============================================================================================
                                                                       
SHORT-TERM INVESTMENTS -- 15.2%

U.S. TREASURY BILLS -- 15.2%
     $2,487,000     U.S. Treasury Bills, 1.087% due 6/5/03 (Cost-- $2,484,370)  $ 2,484,370
=============================================================================================
                    TOTAL INVESTMENTS -- 100%
                    (Cost-- $17,953,990**)                                      $16,332,094
=============================================================================================
 *   NON-INCOME PRODUCING SECURITY.
**   AGGREGATE COST FOR FEDERAL INCOME TAX PURPOSES IS SUBSTANTIALLY THE SAME.








                       SEE NOTES TO FINANCIAL STATEMENTS.

  2  SMITH BARNEY SECTOR SERIES INC. | 2003 Semi-Annual Report to Shareholders


STATEMENT OF ASSETS AND LIABILITIES (UNAUDITED)                   APRIL 30, 2003



ASSETS:
                                                                             
     Investments, at value (Cost-- $15,469,620)                                 $13,847,724
     Short-term investments, at value (Cost-- $2,484,370)                         2,484,370
     Dividends and interest receivable                                                3,287
- ---------------------------------------------------------------------------------------------
     TOTAL ASSETS                                                                16,335,381
- ---------------------------------------------------------------------------------------------

LIABILITIES:
     Management fee payable                                                          38,260
     Bank overdraft                                                                  25,461
     Distribution fees payable                                                       10,117
     Payable for Fund shares purchased                                                4,930
     Accrued expenses                                                                20,993
- ---------------------------------------------------------------------------------------------
     TOTAL LIABILITIES                                                               99,761
- ---------------------------------------------------------------------------------------------
TOTAL NET ASSETS                                                                $16,235,620
=============================================================================================

NET ASSETS:
     Par value of capital shares                                                $     3,342
     Capital paid in excess of par value                                         40,312,702
     Accumulated net investment loss                                               (157,276)
     Accumulated net realized loss from security transactions                   (22,301,743)
     Net unrealized depreciation of investments and foreign currencies           (1,621,405)
- ---------------------------------------------------------------------------------------------
TOTAL NET ASSETS                                                                $16,235,620
=============================================================================================

SHARES OUTSTANDING:
     Class A                                                                        928,062
     --------------------------------------------------------------------------------------
     Class B                                                                      1,022,043
     --------------------------------------------------------------------------------------
     Class L                                                                      1,391,986
     --------------------------------------------------------------------------------------
NET ASSET VALUE:

     Class A (and redemption price)                                                   $4.93
     --------------------------------------------------------------------------------------
     Class B *                                                                        $4.83
     --------------------------------------------------------------------------------------
     Class L **                                                                       $4.83
     --------------------------------------------------------------------------------------
MAXIMUM PUBLIC OFFERING PRICE PER SHARE:

     Class A (net asset value plus 5.26% of net asset value per share)                $5.19
     --------------------------------------------------------------------------------------
     Class L (net asset value plus 1.01% of net asset value per share)                $4.88
============================================================================================

 *   REDEMPTION PRICE IS NAV OF CLASS B SHARES REDUCED BY A 5.00% CDSC IF SHARES
     ARE REDEEMED LESS THAN ONE YEAR FROM INITIAL PURCHASE (SEE NOTE 2).
**   REDEMPTION PRICE IS NAV OF CLASS L SHARES REDUCED BY A 1.00% CDSC IF SHARES
     ARE REDEEMED WITHIN THE FIRST YEAR OF PURCHASE (SEE NOTE 2).







                       SEE NOTES TO FINANCIAL STATEMENTS.

  3  SMITH BARNEY SECTOR SERIES INC. | 2003 Semi-Annual Report to Shareholders


STATEMENT OF OPERATIONS (UNAUDITED)      FOR THE SIX MONTHS ENDED APRIL 30, 2003



INVESTMENT INCOME:
                                                                             
     Dividends                                                                      $ 2,613
     Interest                                                                         2,500
- ---------------------------------------------------------------------------------------------
     TOTAL INVESTMENT INCOME                                                          5,113
- ---------------------------------------------------------------------------------------------

EXPENSES:
     Management fee (Note 2)                                                         74,847
     Distribution fees (Note 6)                                                      62,689
     Shareholder servicing fees (Note 6)                                             14,842
     Custody                                                                         11,856
     Directors' fees                                                                  5,837
     Audit and legal                                                                  5,340
     Registration fees                                                                4,842
     Other                                                                            5,792
- ---------------------------------------------------------------------------------------------
     TOTAL EXPENSES                                                                 186,045
     Less: Management fee waiver (Note 2)                                           (24,872)
- ---------------------------------------------------------------------------------------------
     NET EXPENSES                                                                   161,173
- ---------------------------------------------------------------------------------------------
NET INVESTMENT LOSS                                                                (156,060)
- ---------------------------------------------------------------------------------------------

REALIZED AND UNREALIZED GAIN (LOSS) ON INVESTMENTS
AND FOREIGN CURRENCIES (NOTE 3):
     Realized Gain (Loss) From:
         Security transactions (excluding short-term securities)                 (2,728,133)
         Foreign currency transactions                                                  112
- ---------------------------------------------------------------------------------------------
     NET REALIZED LOSS                                                           (2,728,021)
- ---------------------------------------------------------------------------------------------

     Change in Net Unrealized Depreciation From:
         Security transactions                                                    4,701,623
         Foreign currency transactions                                                  491
- ---------------------------------------------------------------------------------------------
     DECREASE IN NET UNREALIZED DEPRECIATION                                      4,702,114
- ---------------------------------------------------------------------------------------------
NET GAIN ON INVESTMENTS AND FOREIGN CURRENCIES                                    1,974,093
- ---------------------------------------------------------------------------------------------
INCREASE IN NET ASSETS FROM OPERATIONS                                          $ 1,818,033
=============================================================================================








                       SEE NOTES TO FINANCIAL STATEMENTS.

  4  SMITH BARNEY SECTOR SERIES INC. | 2003 Semi-Annual Report to Shareholders


STATEMENTS OF CHANGES IN NET ASSETS

FOR THE SIX MONTHS ENDED APRIL 30, 2003 (UNAUDITED)
AND THE YEAR ENDED OCTOBER 31, 2002



                                                                    2003           2002
=============================================================================================
                                                                          
OPERATIONS:
     Net investment loss                                       $  (156,060)     $  (447,925)
     Net realized loss                                          (2,728,021)      (8,833,953)
     (Increase) decrease in net unrealized depreciation          4,702,114         (456,256)
- ---------------------------------------------------------------------------------------------
     INCREASE (DECREASE) IN NET ASSETS FROM OPERATIONS           1,818,033       (9,738,134)
- ---------------------------------------------------------------------------------------------

FUND SHARE TRANSACTIONS (NOTE 7):
     Net proceeds from sale of shares                              252,161        4,460,547
     Cost of shares reacquired                                  (2,459,842)      (6,533,716)
- ---------------------------------------------------------------------------------------------
     DECREASE IN NET ASSETS FROM FUND SHARE TRANSACTIONS        (2,207,681)      (2,073,169)
- ---------------------------------------------------------------------------------------------
DECREASE IN NET ASSETS                                            (389,648)     (11,811,303)

NET ASSETS:
     Beginning of period                                        16,625,268       28,436,571
- ---------------------------------------------------------------------------------------------
     END OF PERIOD*                                            $16,235,620      $16,625,268
=============================================================================================
* Includes accumulated net investment loss of:                   $(157,276)         $(1,328)
=============================================================================================








                       SEE NOTES TO FINANCIAL STATEMENTS.

  5  SMITH BARNEY SECTOR SERIES INC. | 2003 Semi-Annual Report to Shareholders


NOTES TO FINANCIAL STATEMENTS (UNAUDITED)

1. SIGNIFICANT ACCOUNTING POLICIES

The Smith Barney  Biotechnology Fund ("Fund"), a separate investment fund of the
Smith  Barney  Sector  Series  Inc.  ("Series"),  a  Maryland  corporation,   is
registered   under  the   Investment   Company  of  1940,   as  amended,   as  a
non-diversified,  open-end management investment company. The Series consists of
three other separate  investment  funds:  Smith Barney Financial  Services Fund,
Smith Barney  Health  Sciences Fund  ("Health  Sciences  Fund") and Smith Barney
Technology  Fund.  As of May 9, 2003,  the Fund merged into the Health  Sciences
Fund. The financial  statements and financial highlights for the other funds are
presented in separate shareholder reports.

The  significant  accounting  policies  followed by the Fund are:  (a)  security
transactions are accounted for on trade date; (b) securities  traded in national
securities  markets are valued at the closing prices in the primary  exchange on
which they are traded;  securities listed or traded on certain foreign exchanges
or other  markets  whose  operations  are  similar to the U.S.  over-the-counter
market  (including  securities  listed on exchanges  where the primary market is
believed to be  over-the-counter)  and securities for which no sale was reported
on that date are valued at the mean between the bid and asked prices; securities
listed on the NASDAQ  National  Market  System for which market  quotations  are
available  are valued at the official  closing price or, if there is no official
closing price on that day, at the last sale price.  Securities  which are listed
or traded on more than one  exchange or market are valued at the  quotations  on
the exchange or market  determined to be the primary market for such securities;
(c) securities  for which market  quotations are not available will be valued in
good  faith at fair  market  value by or under  the  direction  of the  Board of
Directors;  (d)  securities  maturing  within  60 days are  valued  at cost plus
accreted discount, or minus amortized premium, which approximates value; (e) the
accounting  records of the Fund are maintained in U.S.  dollars.  All assets and
liabilities  denominated in foreign  currencies are translated into U.S. dollars
based on the rate of exchange of such  currencies  against  U.S.  dollars on the
date of valuation.  Purchases and sales of  securities,  and income and expenses
are translated at the rate of exchange  quoted on the respective  date that such
transactions  are  recorded.  Differences  between  income  or  expense  amounts
recorded and collected or paid are adjusted when reported by the custodian;  (f)
interest income, adjusted for amortization of premium and accretion of discount,
is  recorded  on an  accrual  basis;  (g)  dividend  income is  recorded  on the
ex-dividend  date;  foreign dividends are recorded on the ex-dividend date or as
soon as  practical  after  the  Fund  determines  the  existence  of a  dividend
declaration  after  exercising  reasonable  due  diligence;  (h)  dividends  and
distributions  to shareholders  are recorded on the  ex-dividend  date; the Fund
distributes  dividends and capital gains, if any, annually;  (i) gains or losses
on the sale of securities  are  calculated by using the specific  identification
method;  (j) direct  expenses  are  charged to each class;  management  fees and
general Fund expenses are allocated on the basis of relative net assets; (k) the
Fund intends to comply with the  requirements  of the  Internal  Revenue Code of
1986,  as amended,  pertaining  to regulated  investment  companies  and to make
distributions of taxable income sufficient to relieve it from  substantially all
Federal  income and excise  taxes;  (l) the  character of income and gains to be
distributed  in  accordance  with income tax  regulations  which may differ from
accounting  principles  generally accepted in the United States of America;  and
(m)  estimates  and  assumptions  are  required  to be  made  regarding  assets,
liabilities  and changes in net assets  resulting from operations when financial
statements are prepared. Changes in the economic environment,  financial markets
and any other parameters used in determining  these estimates could cause actual
results to differ.

In  addition,  the Fund may enter into  forward  exchange  contracts in order to
hedge against foreign currency risk. These contracts are marked-to-market daily,
by recognizing the difference between the contract exchange rate and the current
market  rate as an  unrealized  gain or  loss.  Realized  gains  or  losses  are
recognized when contracts are settled.






  6  SMITH BARNEY SECTOR SERIES INC. | 2003 Semi-Annual Report to Shareholders


NOTES TO FINANCIAL STATEMENTS (UNAUDITED) (CONTINUED)

2. MANAGEMENT AGREEMENT AND OTHER TRANSACTIONS

Smith Barney Fund Management LLC ("SBFM"), an indirect  wholly-owned  subsidiary
of Citigroup  Inc.  ("Citigroup"),  acts as investment  manager to the Fund. The
management fee is calculated at an annual rate of 0.95% of the average daily net
assets.  This fee is calculated  daily and paid monthly.  SBFM has delegated the
daily management of the Fund to Citigroup Asset Management Ltd. ("CAM Ltd."), an
affiliate  of SBFM.  For  services  provided  to the Fund,  SBFM pays CAM Ltd. a
subadvisory  fee computed at an annual rate of 0.65% of the Fund's average daily
net assets.  For the six months ended April 30,  2003,  SBFM waived a portion of
its management fee amounting to $24,872.

Citicorp Trust Bank, fsb. ("CTB"), another subsidiary of Citigroup,  acts as the
Fund's  transfer  agent.  PFPC Global Fund Services  ("PFPC") acts as the Fund's
sub-transfer  agent.  CTB receives  account fees and asset-based  fees that vary
according to the size and type of account.  PFPC is responsible  for shareholder
recordkeeping and financial  processing for all shareholder accounts and is paid
by CTB. For the six months ended April 30, 2003,  the Fund paid  transfer  agent
fees of $7,874 to CTB.

Citigroup  Global Markets Inc.  ("CGM"),  formerly known as Salomon Smith Barney
Inc., another indirect wholly-owned subsidiary of Citigroup,  acts as the Fund's
distributor.  In addition, CGM and certain other broker-dealers continue to sell
Fund  shares to the public as members of the selling  group.  For the six months
ended April 30, 2003, CGM did not receive any brokerage commissions.

There are  maximum  initial  sales  charges of 5.00% and 1.00% for Class A and L
shares,  respectively.  There is a contingent  deferred sales charge ("CDSC") of
5.00% on Class B shares, which applies if redemption occurs within one year from
initial  purchase  and  declines  thereafter  by 1.00% per year until no CDSC is
incurred.  Class L shares also have a 1.00% CDSC,  which  applies if  redemption
occurs within the first year of purchase.  In certain cases, Class A shares have
a 1.00%  CDSC,  which  applies  if  redemption  occurs  within the first year of
purchase.  This CDSC only applies to those  purchases of Class A shares,  which,
when  combined  with  current  holdings  of  Class A  shares,  equal  or  exceed
$1,000,000  in the  aggregate.  These  purchases  do not incur an initial  sales
charge.

For the six  months  ended  April  30,  2003,  CGM  received  sales  charges  of
approximately  $3,000 and  $1,000 on sales of the  Fund's  Class A and L shares,
respectively.  In addition,  for the six months ended April 30, 2003, CDSCs paid
to CGM were approximately $20,000 for Class B shares.

All officers  and one  Director of the Series are  employees of Citigroup or its
affiliates.

3. INVESTMENTS

During the six months ended April 30, 2003,  the aggregate cost of purchases and
proceeds  from  sales  of   investments   (including   maturities  of  long-term
securities, but excluding short-term securities) were as follows:


================================================================================
Purchases                                                            $1,907,993
- --------------------------------------------------------------------------------
Sales                                                                 6,212,518
================================================================================

At April 30, 2003, the aggregate gross unrealized  appreciation and depreciation
of investments for Federal income tax purposes were substantially as follows:

================================================================================
Gross unrealized appreciation                                        $  746,468
Gross unrealized depreciation                                        (2,368,364)
- --------------------------------------------------------------------------------
Net unrealized depreciation                                         $(1,621,896)
================================================================================






  7  SMITH BARNEY SECTOR SERIES INC. | 2003 Semi-Annual Report to Shareholders


NOTES TO FINANCIAL STATEMENTS (UNAUDITED) (CONTINUED)

4. REPURCHASE AGREEMENTS

The Fund  purchases  (and its custodian  takes  possession  of) U.S.  government
securities  from  securities   dealers  subject  to  agreements  to  resell  the
securities to the sellers at a future date (generally, the next business day) at
an agreed upon higher repurchase price. The Fund requires continual  maintenance
of the market  value (plus  accrued  interest) of the  collateral  in amounts at
least equal to the repurchase price.

At April 30, 2003, the Fund did not have any repurchase agreements outstanding.

5. CONCENTRATION OF RISK

The Fund normally  invests at least 80% of its assets in  biotechnology  related
investments. As a result of this concentration policy, the Fund's investment may
be subject to greater  risk and market  fluctuation  than a fund that invests in
securities representing a broader range of investment alternatives.

6. CLASS SPECIFIC EXPENSES

Pursuant to a  Distribution  Plan,  the Fund pays a service fee with  respect to
Class A, B and L shares  calculated  at an annual  rate of 0.25% of the  average
daily assets of each  respective  class.  The Fund also pays a distribution  fee
with  respect to Class B and L shares  calculated  at an annual rate of 0.75% of
the  average  daily net assets of each class,  respectively.  For the six months
ended April 30, 2003, total  Distribution Plan fees incurred,  which are accrued
daily and paid monthly, were as follows:

                                                CLASS A     CLASS B     CLASS L
================================================================================
Distribution Plan Fees                          $5,366      $24,398     $32,925
================================================================================


For the six months ended April 30, 2003, total Shareholder Servicing fees were
as follows:

                                                CLASS A     CLASS B     CLASS L
================================================================================
Shareholder Servicing Fees                      $4,048       $4,595      $6,199
================================================================================

7. CAPITAL SHARES

At April 30, 2003, the Fund had 400 million  shares of capital stock  authorized
with a par value of $0.001 per share. The Fund has the ability to issue multiple
classes of shares. Each share of a class represents an identical interest in the
Fund and has the same  rights,  except  that each class bears  certain  expenses
specifically related to the distribution of its shares.

Transactions in shares of each class were as follows:



                                             SIX MONTHS ENDED                    YEAR ENDED
                                              APRIL 30, 2003                  OCTOBER 31, 2002
                                           ---------------------            ---------------------
                                           SHARES        AMOUNT            SHARES         AMOUNT
==================================================================================================
                                                                           
CLASS A
Shares sold                                 24,216       $106,790         423,275      $1,993,470
Shares reacquired                         (104,478)      (464,078)       (420,496)     (2,260,800)
- --------------------------------------------------------------------------------------------------
Net Increase (Decrease)                    (80,262)     $(357,288)          2,779       $(267,330)
==================================================================================================







  8  SMITH BARNEY SECTOR SERIES INC. | 2003 Semi-Annual Report to Shareholders


Notes to Financial Statements (unaudited) (continued)




                                             SIX MONTHS ENDED                    YEAR ENDED
                                              APRIL 30, 2003                  OCTOBER 31, 2002
                                           ---------------------            ---------------------
                                           SHARES        AMOUNT            SHARES         AMOUNT
===================================================================================================
                                                                           
CLASS B
Shares sold                                 18,796       $    83,104        186,576    $ 1,120,984
Shares reacquired                         (193,382)         (834,531)      (291,729)    (1,497,102)
- ---------------------------------------------------------------------------------------------------
Net Decrease                              (174,586)      $  (751,427)      (105,153)   $  (376,118)
===================================================================================================
CLASS L
Shares sold                                 14,264       $    62,267        233,275    $ 1,346,093
Shares reacquired                         (266,484)       (1,161,233)      (534,242)    (2,775,814)
- ---------------------------------------------------------------------------------------------------
Net Decrease                              (252,220)      $(1,098,966)      (300,967)   $(1,429,721)
===================================================================================================



8. SUBSEQUENT EVENT

On January 29,  2003,  the Board of  Directors  of the Series,  on behalf of the
Fund, approved a proposed  reorganization  pursuant to which the Health Sciences
Fund, a separate  investment  fund of the Series,  would  acquire the assets and
assume the stated  liabilities  of the Fund in exchange for shares of the Health
Sciences  Fund.  This  reorganization  will  allow the  Fund's  shareholders  to
maintain  an  investment  in a fund  with  the  same  investment  objective  and
substantially  similar investment policies.  On May 7, 2003, the shareholders of
the Fund approved the  reorganization of the Fund into the Health Sciences Fund.
The effective date of the reorganization was May 9, 2003.










  9  SMITH BARNEY SECTOR SERIES INC. | 2003 Semi-Annual Report to Shareholders


FINANCIAL HIGHLIGHTS

FOR A SHARE OF EACH CLASS OF CAPITAL STOCK OUTSTANDING THROUGHOUT EACH YEAR
ENDED OCTOBER 31, UNLESS OTHERWISE NOTED:



CLASS A SHARES                                             2003(1)(2)        2002(2)            2001            2000(2)(3)
==========================================================================================================================
                                                                                                    
NET ASSET VALUE, BEGINNING OF PERIOD                       $4.37              $6.73             $9.88           $11.40
- --------------------------------------------------------------------------------------------------------------------------
INCOME (LOSS) FROM OPERATIONS:

   Net investment loss(4)                                  (0.03)             (0.08)            (0.10)           (0.04)
   Net realized and unrealized gain (loss)                  0.59              (2.28)            (3.05)           (1.48)
- --------------------------------------------------------------------------------------------------------------------------
Total Income (Loss) From Operations                         0.56              (2.36)            (3.15)           (1.52)
- --------------------------------------------------------------------------------------------------------------------------
NET ASSET VALUE, END OF PERIOD                             $4.93              $4.37             $6.73           $ 9.88
- --------------------------------------------------------------------------------------------------------------------------
TOTAL RETURN                                               12.81%++          (35.07)%          (31.88)%         (13.33)%++
- --------------------------------------------------------------------------------------------------------------------------
NET ASSETS, END OF PERIOD (000S)                          $4,573             $4,407            $6,769           $8,486
- --------------------------------------------------------------------------------------------------------------------------
RATIOS TO AVERAGE NET ASSETS:
   Expenses(4)(5)                                           1.50%+             1.48%             1.50%            1.52%+
   Net investment loss                                     (1.43)+            (1.41)            (1.40)           (0.78)+
- --------------------------------------------------------------------------------------------------------------------------
PORTFOLIO TURNOVER RATE                                       12%                91%               74%               1%
==========================================================================================================================


(1) FOR THE SIX MONTHS ENDED APRIL 30, 2003 (UNAUDITED).

(2) PER SHARE AMOUNTS HAVE BEEN CALCULATED USING THE MONTHLY AVERAGE SHARES
    METHOD.

(3) FOR THE PERIOD FROM AUGUST 31, 2000 (INCEPTION DATE) TO OCTOBER 31, 2000.

(4) THE MANAGER WAIVED A PORTION OF ITS FEES FOR THE SIX MONTHS ENDED APRIL 30,
    2003, THE YEARS ENDED OCTOBER 31, 2002 AND 2001, AND THE PERIOD ENDED
    OCTOBER 31, 2000. IF SUCH FEES WERE NOT WAIVED, THE PER SHARE INCREASES TO
    NET INVESTMENT LOSS AND THE ACTUAL EXPENSE RATIOS WOULD HAVE BEEN AS
    FOLLOWS:



                               Per Share Increases to                     Expense Ratios
                                Net Investment Loss                     Without Fee Waiver
                         ----------------------------------      ---------------------------------
                           2003      2002     2001    2000        2003      2002    2001     2000
                         -------    ------   ------  ------      ------    ------  ------   ------
                                                                     
      Class A Shares      $0.01     $0.03    $0.04    $0.00*     1.82%+     1.98%   1.98%    3.08%+


(5) AS A RESULT OF A VOLUNTARY EXPENSE  LIMITATION,  THE RATIO OF EXPENSES TO
    AVERAGE NET ASSETS WILL NOT EXCEED 1.50% FOR CLASS A SHARES.

 *  AMOUNT REPRESENTS LESS THAN $0.01 PER SHARE.

 ++ TOTAL RETURN IS NOT ANNUALIZED, AS IT MAY NOT BE REPRESENTATIVE OF THE TOTAL
    RETURN FOR THE YEAR.

 +  ANNUALIZED.









 10  SMITH BARNEY SECTOR SERIES INC. | 2003 Semi-Annual Report to Shareholders


FINANCIAL HIGHLIGHTS (CONTINUED)

FOR A SHARE OF EACH CLASS OF CAPITAL STOCK OUTSTANDING THROUGHOUT EACH YEAR
ENDED OCTOBER 31, UNLESS OTHERWISE NOTED:



CLASS B SHARES                                             2003(1)(2)        2002(2)            2001            2000(2)(3)
==========================================================================================================================
                                                                                                    
NET ASSET VALUE, BEGINNING OF PERIOD                       $4.30              $6.67             $9.86           $11.40
- --------------------------------------------------------------------------------------------------------------------------
INCOME (LOSS) FROM OPERATIONS:
   Net investment loss(4)                                  (0.05)             (0.12)            (0.16)           (0.05)
   Net realized and unrealized gain (loss)                  0.58              (2.25)            (3.03)           (1.49)
- --------------------------------------------------------------------------------------------------------------------------
Total Income (Loss) From Operations                         0.53              (2.37)            (3.19)           (1.54)
- --------------------------------------------------------------------------------------------------------------------------
NET ASSET VALUE, END OF PERIOD                             $4.83              $4.30             $6.67           $ 9.86
- --------------------------------------------------------------------------------------------------------------------------
TOTAL RETURN                                               12.33%++          (35.53)%          (32.35)%         (13.51)%++
- --------------------------------------------------------------------------------------------------------------------------
NET ASSETS, END OF PERIOD (000S)                          $4,938             $5,147            $8,687          $11,705
- --------------------------------------------------------------------------------------------------------------------------
RATIOS TO AVERAGE NET ASSETS:
   Expenses(4)(5)                                           2.25%+             2.24%             2.25%            2.28%+
   Net investment loss                                     (2.19)+            (2.17)            (2.15)           (1.51)+
- --------------------------------------------------------------------------------------------------------------------------
PORTFOLIO TURNOVER RATE                                       12%                91%               74%               1%
==========================================================================================================================


(1) FOR THE SIX MONTHS ENDED APRIL 30, 2003 (UNAUDITED).

(2) PER SHARE AMOUNTS HAVE BEEN CALCULATED USING THE MONTHLY AVERAGE SHARES
    METHOD.

(3) FOR THE PERIOD FROM AUGUST 31, 2000 (INCEPTION DATE) TO OCTOBER 31, 2000.

(4) THE MANAGER WAIVED A PORTION OF ITS FEES FOR THE SIX MONTHS ENDED APRIL 30,
    2003, THE YEARS ENDED OCTOBER 31, 2002 AND 2001, AND THE PERIOD ENDED
    OCTOBER 31, 2000. IF SUCH FEES WERE NOT WAIVED, THE PER SHARE INCREASES TO
    NET INVESTMENT LOSS AND THE ACTUAL EXPENSE RATIOS WOULD HAVE BEEN AS
    FOLLOWS:



                               Per Share Increases to                     Expense Ratios
                                Net Investment Loss                     Without Fee Waiver
                         ----------------------------------      ---------------------------------
                           2003      2002     2001    2000        2003      2002    2001     2000
                         -------    ------   ------  ------      ------    ------  ------   ------
                                                                     
         Class B Shares   $0.01     $0.03    $0.03    $0.00*     2.56%+     2.77%   2.74%    3.84%+


(5) AS A RESULT OF A VOLUNTARY EXPENSE  LIMITATION,  THE RATIO OF EXPENSES TO
    AVERAGE NET ASSETS WILL NOT EXCEED 2.25% FOR CLASS B SHARES.

 *  AMOUNT REPRESENTS LESS THAN $0.01 PER SHARE.

 ++ TOTAL RETURN IS NOT ANNUALIZED, AS IT MAY NOT BE REPRESENTATIVE OF THE TOTAL
    RETURN FOR THE YEAR.

 +  ANNUALIZED.





 11  SMITH BARNEY SECTOR SERIES INC. | 2003 Semi-Annual Report to Shareholders


FINANCIAL HIGHLIGHTS (CONTINUED)

FOR A SHARE OF EACH CLASS OF CAPITAL STOCK OUTSTANDING THROUGHOUT EACH YEAR
ENDED OCTOBER 31, UNLESS OTHERWISE NOTED:



CLASS L SHARES                                             2003(1)(2)        2002(2)            2001            2000(2)(3)
==========================================================================================================================
                                                                                                    
NET ASSET VALUE, BEGINNING OF PERIOD                       $4.30              $6.67              $9.86           $11.40
- --------------------------------------------------------------------------------------------------------------------------
INCOME (LOSS) FROM OPERATIONS:
   Net investment loss(4)                                  (0.05)             (0.12)             (0.16)           (0.06)
   Net realized and unrealized gain (loss)                  0.58              (2.25)             (3.03)           (1.48)
- --------------------------------------------------------------------------------------------------------------------------
Total Income (Loss) From Operations                         0.53              (2.37)             (3.19)           (1.54)
- --------------------------------------------------------------------------------------------------------------------------
NET ASSET VALUE, END OF PERIOD                             $4.83              $4.30              $6.67           $ 9.86
- --------------------------------------------------------------------------------------------------------------------------
TOTAL RETURN                                               12.33%++          (35.53)%           (32.35)%         (13.51)%++
- --------------------------------------------------------------------------------------------------------------------------
NET ASSETS, END OF PERIOD (000S)                          $6,725             $7,071            $12,980          $15,763
- --------------------------------------------------------------------------------------------------------------------------
RATIOS TO AVERAGE NET ASSETS:
   Expenses(4)(5)                                           2.25%+             2.24%              2.25%            2.28%+
   Net investment loss                                     (2.18)+            (2.17)             (2.15)           (1.51)+
- --------------------------------------------------------------------------------------------------------------------------
PORTFOLIO TURNOVER RATE                                       12%                91%                74%               1%
==========================================================================================================================


(1) FOR THE SIX MONTHS ENDED APRIL 30, 2003 (UNAUDITED).

(2) PER SHARE AMOUNTS HAVE BEEN CALCULATED USING THE MONTHLY AVERAGE SHARES
    METHOD.

(3) FOR THE PERIOD FROM AUGUST 31, 2000 (INCEPTION DATE) TO OCTOBER 31, 2000.

(4) THE MANAGER WAIVED A PORTION OF ITS FEES FOR THE SIX MONTHS ENDED APRIL 30,
    2003, THE YEARS ENDED OCTOBER 31, 2002 AND 2001, AND THE PERIOD ENDED
    OCTOBER 31, 2000. IF SUCH FEES WERE NOT WAIVED, THE PER SHARE INCREASES TO
    NET INVESTMENT LOSS AND THE ACTUAL EXPENSE RATIOS WOULD HAVE BEEN AS
    FOLLOWS:



                               Per Share Increases to                     Expense Ratios
                                Net Investment Loss                     Without Fee Waiver
                         ----------------------------------      ---------------------------------
                           2003      2002     2001    2000        2003      2002    2001     2000
                         -------    ------   ------  ------      ------    ------  ------   ------
                                                                     
         Class L Shares   $0.01     $0.03    $0.03    $0.00*     2.57%+     2.75%   2.74%    3.84%+


(5) AS A RESULT OF A VOLUNTARY EXPENSE  LIMITATION,  THE RATIO OF EXPENSES TO
    AVERAGE NET ASSETS WILL NOT EXCEED 2.25% FOR CLASS L SHARES.

 *  AMOUNT REPRESENTS LESS THAN $0.01 PER SHARE.

 ++ TOTAL RETURN IS NOT ANNUALIZED, AS IT MAY NOT BE REPRESENTATIVE OF THE TOTAL
    RETURN FOR THE YEAR.

 +  ANNUALIZED.


ADDITIONAL SHAREHOLDER INFORMATION (UNAUDITED)

On May 7, 2003, a special meeting of the shareholders of the Fund was held for
the purpose of voting on the following matter:

     1.   To approve the Series' Plan of  Reorganization  providing  for (i) the
          acquisition  of all the  assets  and  liabilities  of the  Fund by the
          Health Sciences Fund  ("Acquiring  Fund"),  also an investment fund of
          the Series,  (ii) the amendment of the Series'  Charter  reclassifying
          all shares of the Fund as shares of the Acquiring  Fund, and (iii) the
          accomplishment  of the  reclassification  by the issuance of shares of
          the Acquiring Fund to shareholders of the Fund.

The results of the vote on Proposal 1 were as follows:



                               % OF                   VOTES                   % OF                  VOTES                % OF SHARES
     VOTES FOR             SHARES VOTED              AGAINST              SHARES VOTED             ABSTAINED                VOTED
====================================================================================================================================
                                                                                                             
   1,786,604.291              86.29%               188,523.376                9.11%               95,311.145                4.60%
====================================================================================================================================





 12  SMITH BARNEY SECTOR SERIES INC. | 2003 Semi-Annual Report to Shareholders


SMITH BARNEY
BIOTECHNOLOGY FUND

     DIRECTORS
     Herbert Barg
     Dwight B. Crane
     Burt N. Dorsett
     R. Jay Gerken, Chairman
     Elliot S. Jaffe
     Stephen E. Kaufman
     Joseph J. McCann
     Cornelius C. Rose, Jr.

     OFFICERS
     R. Jay Gerken
     President and Chief
     Executive Officer

     Lewis E. Daidone
     Senior Vice President and
     Chief Administrative Officer

     Richard L. Peteka
     Chief Financial Officer
     and Treasurer

     Kaprel Ozsolak
     Controller

     Christina T. Sydor
     Secretary

     INVESTMENT MANAGER
     Smith Barney Fund Management LLC

     INVESTMENT SUB-ADVISER
     Citigroup Asset Management Ltd.

     DISTRIBUTORS
     Citigroup Global Markets Inc.

     CUSTODIAN
     State Street Bank and
       Trust Company

     TRANSFER AGENT
     Citicorp Trust Bank, fsb.
     125 Broad Street, 11th Floor
     New York, New York 10004

     SUB-TRANSFER AGENTS
     PFPC Global Fund Services
     P.O. Box 9699
     Providence, Rhode Island
     02940-9699




SMITH BARNEY BIOTECHNOLOGY FUND
- --------------------------------------------------------------------------------

This report is submitted for the general information of the shareholders of
Smith Barney Sector Series Inc. -- Smith Barney Health Sciences Fund, but it may
also be used as sales literature when preceded or accompanied by the current
Prospectus, which gives details about charges, expenses, investment objectives
and operating policies of the Fund. If used as sales material after July 31,
2003, this report must be accompanied by performance information for the most
recently completed calendar quarter.

SMITH BARNEY HEALTH SCIENCES FUND
Smith Barney Mutual Funds
125 Broad Street
10th Floor, MF-2
New York, New York 10004

For complete information on any Smith Barney Mutual Funds, including management
fees and expenses, call or write your financial professional for a free
prospectus. Read it carefully before you invest or send money.

www.smithbarneymutualfunds.com

(C)2003 Citigroup Global Markets Inc.
Member NASD, SIPC

FD02550 6/03                                                             03-4964



ITEM 2.  CODE OF ETHICS.

         Not applicable.

ITEM 3.  AUDIT COMMITTEE FINANCIAL EXPERT.

         Not applicable.

ITEM 4.  PRINCIPAL ACCOUNTANT FEES AND SERVICES.

         Not applicable.

ITEM 5.  AUDIT COMMITTEE OF LISTED REGISTRANTS.

         Not applicable.

ITEM 6.  [RESERVED]

ITEM 7.  DISCLOSURE OF PROXY VOTING POLICIES AND PROCEDURES FOR CLOSED-END
         MANAGEMENT INVESTMENT COMPANIES.

         Not applicable.

ITEM 8.  [RESERVED]

ITEM 9.  CONTROLS AND PROCEDURES.

         (a)  The registrant's principal executive officer and principal
              financial officer have concluded that the registrant's disclosure
              controls and procedures (as defined in Rule 30a-2(c) under the
              Investment Company Act of 1940, as amended) are effective based
              on their evaluation of the disclosure controls and procedures as
              of a date within 90 days of the filing date of this document.

         (b)  In the last 90 days, there have been no significant changes in
              the Registrant's internal controls or in other factors that could
              significantly affect these controls.

ITEM 10. EXHIBITS.

         (a)  Not applicable.

         (b)  Attached hereto.

         Exhibit 99.CERT      Certifications pursuant to section 302 of the
                              Sarbanes-Oxley Act of 2002

         Exhibit 99.906CERT   Certifications pursuant to Section 906 of the
                              Sarbanes-Oxley Act of 2002

SIGNATURES

     Pursuant to the requirements of the Securities Exchange Act of 1934 and the
Investment Company Act of 1940, the registrant has duly caused this Report to be
signed on its behalf by the undersigned, there unto duly authorized.




SMITH BARNEY SECTOR SERIES INC.

By:      /s/ R. Jay Gerken
         R. Jay Gerken
         Chief Executive Officer of
         Smith Barney Sector Series Inc.

Date:    July 2, 2003

     Pursuant to the requirements of the Securities Exchange Act of 1934 and the
Investment Company Act of 1940, this report has been signed below by the
following persons on behalf of the registrant and in the capacities and on the
dates indicated.

By:      /s/ R. Jay Gerken
         (R. Jay Gerken)
         Chief Executive Officer of
         Smith Barney Sector Series Inc.

Date:    July 2, 2003

By:      /s/ RICHARD PETEKA
         Chief Financial Officer of
         Smith Barney Sector Series Inc.

Date:    July 2, 2003