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)

Robert I. Frenkel, Esq.
Smith Barney Fund Management LLC
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, 2004

ITEM 1.  REPORT TO STOCKHOLDERS.

         The Semi-Annual Report to Stockholders is filed herewith.

                            ------------------------
                                  SMITH BARNEY
                               SECTOR SERIES INC.
                                  SMITH BARNEY
                              HEALTH SCIENCES FUND
                            ------------------------

              RESEARCH SERIES | SEMI-ANNUAL REPORT | APRIL 30, 2004




                    [SMITH BARNEY MUTUAL FUNDS LOGO OMITTED]

   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, 2004

SMITH BARNEY
HEALTH SCIENCES FUND


WHAT'S INSIDE

LETTER FROM THE CHAIRMAN ...................................................   1
SCHEDULE OF INVESTMENTS ....................................................   4
STATEMENT OF ASSETS AND LIABILITIES ........................................   5
STATEMENT OF OPERATIONS ....................................................   6
STATEMENTS OF CHANGES IN NET ASSETS ........................................   7
NOTES TO FINANCIAL STATEMENTS ..............................................   8
FINANCIAL HIGHLIGHTS .......................................................  13


SMITH BARNEY FUND MANAGEMENT LLC

Smith Barney Fund Management LLC is the investment manager to the fund.
Citigroup Asset Management Limited is the sub-adviser. 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 by investing primarily in common
stocks. The fund normally invests at least 80% of its assets in securities of
companies principally engaged in the design, manufacture, or sale of products or
services used for or in connection with healthcare or medicine.


FUND FACTS

FUND INCEPTION
- --------------------------------------------------------------------------------
February 28, 2000



*  Since the fund focuses its investments on companies involved in the health
   sciences, an investment in the fund may involve a greater degree of risk than
   an investment in other mutual funds with greater diversification.



- --------------------------------------------------------------------------------
                            LETTER FROM THE CHAIRMAN
- --------------------------------------------------------------------------------

DEAR SHAREHOLDER,

Over the six month period ended April 30, 2004, most broad U.S. stock and bond
market indexes posted moderate gains. Stocks generally continued to outpace
bonds, with large-capitalization stocks typically outperforming small- and
mid-cap stocks and international stock markets generally outperforming the
domestic stock market. The economic environment was dominated by uncertainty
surrounding the sustainability of the domestic economic recovery, a continued
focus on new job growth and a geopolitical environment centering on news from
Iraq and new acts of terrorism.

Since the start of 2004, markets have been in a holding pattern -- volatility
declined, and returns were relatively muted. Equity markets seem to have priced
in prospects of continued economic recovery and, in general, they were not
disappointed. Both bond market and stock market participants were a bit unnerved
by prospects for U.S. Federal Reserve Board ("Fed") tightening of key interest
rates at some unknown future date, the continuing turmoil in Iraq, and the March
2004 bombings in Spain. Each of these elements had a


[R. JAY GERKEN PHOTO OMITTED]

R. JAY GERKEN, CFA
CHAIRMAN, PRESIDENT AND
CHIEF EXECUTIVE OFFICER


- --------------------------------------------------------------------------------
                              PERFORMANCE SNAPSHOT
                              AS OF APRIL 30, 2004
                            (EXCLUDING SALES CHARGES)
- --------------------------------------------------------------------------------
                                                                        6 MONTHS
- --------------------------------------------------------------------------------
Class A Shares                                                            10.83%
- --------------------------------------------------------------------------------
Russell 3000 Index                                                         6.14%
- --------------------------------------------------------------------------------
Goldman Sachs Healthcare Index                                            12.55%
- --------------------------------------------------------------------------------
Lipper Health/Biotechnology Funds Category Average                        13.78%
- --------------------------------------------------------------------------------

THE PERFORMANCE SHOWN REPRESENTS PAST PERFORMANCE. PAST PERFORMANCE IS NO
GUARANTEE OF FUTURE RESULTS AND CURRENT PERFORMANCE MAY BE HIGHER OR LOWER THAN
THE PERFORMANCE SHOWN ABOVE. PERFORMANCE FIGURES MAY REFLECT FEE WAIVERS AND/OR
EXPENSE REIMBURSEMENTS, IF ANY. IN THE ABSENCE OF FEE WAIVERS AND/OR EXPENSE
REIMBURSEMENTS, IF ANY, THE TOTAL RETURN WOULD BE REDUCED. PRINCIPAL VALUE AND
INVESTMENT RETURNS WILL FLUCTUATE AND INVESTORS' SHARES, WHEN REDEEMED, MAY BE
WORTH MORE OR LESS THAN THEIR ORIGINAL COST. TO OBTAIN PERFORMANCE DATA CURRENT
TO THE MOST RECENT MONTH-END, PLEASE VISIT OUR WEBSITE AT
WWW.SMITHBARNEYMUTUALFUNDS.COM.

CLASS A SHARE RETURNS ASSUME THE REINVESTMENT OF INCOME DIVIDENDS AND CAPITAL
GAINS DISTRIBUTIONS AT NET ASSET VALUE AND THE DEDUCTION OF ALL FUND EXPENSES.
RETURNS HAVE NOT BEEN ADJUSTED TO INCLUDE SALES CHARGES THAT MAY APPLY WHEN
SHARES ARE PURCHASED OR THE DEDUCTION OF TAXES THAT A SHAREHOLDER WOULD PAY ON
FUND DISTRIBUTIONS. EXCLUDING SALES CHARGES, CLASS B SHARES RETURNED 10.57% AND
CLASS C SHARES RETURNED 10.47% OVER THE SIX MONTHS ENDED APRIL 30, 2004.

Effective April 29, 2004, Smith Barney Class L shares were renamed Class C
shares. On February 2, 2004, initial sales charges on these shares were
eliminated.

All index performance reflects no deduction for fees, expenses or taxes. The
Russell 3000 Index measures the performance of the 3,000 largest U.S. companies
based on total market capitalization, which represent approximately 98% of U.S.
equity market. The Goldman Sachs Healthcare Index is an unmanaged market-value
weighted index comprised of healthcare service companies including long-term
care and hospital facilities, healthcare management organizations and continuing
care services and pharmaceutical companies.

Lipper, Inc. is a major independent mutual-fund tracking organization. Returns
are based on the six-month period ended April 30, 2004, calculated among the 194
funds in the fund's Lipper category including the reinvestment of dividends and
capital gains, if any, and excluding sales charges.


           1 SMITH BARNEY SECTOR SERIES INC. | 2004 Semi-Annual Report


negative influence on the stock market. Despite these concerns, however, the
underlying economic and financial fundamentals continued to improve through the
end of the period.

So far this year, the economy overall has appeared to be growing at a pace
similar to last year's rate. The ongoing recovery has been broad-based, with
strength in the consumer sector, exports and business investments. Soaring
corporate profit growth has led to vastly improved balance-sheet fundamentals in
general, while highly stimulative monetary and fiscal policy continued to
provide support, although the stimulative effects of fiscal policy could wane
after tax-refund season ends this spring. Following a period of mixed employment
news through the end of last year, job growth picked up substantially in the
first calendar quarter of 2004.

Signs of increasing inflation have begun to mount in recent weeks. Fiscal and
monetary policymakers have been stimulating the economy since 2000. The Fed has
more or less said it prefers inflation to deflation in the current environment.
However, we believe the recent pick-up in inflationary signals has increased the
possibility that the Fed may raise interest rates sooner than anticipated,
perhaps as early as this summer. Accordingly, the recent debate in the market
has focused on the timing and magnitude of prospective rate increases.

PERFORMANCE REVIEW

Within this environment, the fund performed as follows: For the six months ended
April 30, 2004, Class A shares of the Smith Barney Health Sciences Fund,
excluding sales charges, returned 10.83%. In comparison the fund's unmanaged
benchmarks, the Russell 3000 Index(i), returned 6.14% and the Goldman Sachs
Healthcare Index(ii), returned 12.55% for the same period. The fund's Lipper
health/biotechnology funds category average returned 13.78% for the same
period.(1)

In the health care sector, the majority of the gains over the six-month period
came between November 2003 and February 2004. The strongest returns in the
sector came from biotechnology, medical device and managed care stocks. Biotech
stocks as a group moved higher as a result of positive developments on several
promising new products. GENENTECH, INC.'S novel anticancer therapy, AVASTIN, was
approved by the FDA, and the company disclosed positive data for TARCEVA, an
agent for treating lung cancer. BIOGEN IDEC INC. also disclosed positive results
for its pipeline drug ANTEGREN for treating multiple sclerosis. Managed care
companies continued to post strong results and consolidation activity was
ongoing. At the close of the period, ANTHEM INC. and WELLPOINT HEALTH NETWORKS,
INC. were on their way to completing their merger, and OXFORD HEALTH PLANS
agreed to be acquired by UNITEDHEALTH GROUP INC. during the period. Medical
device stocks continued to perform well, especially in the orthopaedic area,
where device manufacturers are benefiting from strong growth in procedures.
Large capitalization pharmaceutical stocks performed broadly in line with the
overall healthcare market. Concerns over political uncertainty, lack of new
products and legal challenges to intellectual property were offset by cheap
valuations, a currency tailwind and investor appetitive for defensive growth
stocks.

FUND PERFORMANCE

The fund's underperformance was primarily the result of poor returns from a
number of holdings in different sub-sectors. The fund was negatively impacted by
its holdings in WYETH, which performed poorly as a result of an adverse court
decision on their diet drug litigation. Also detracting from performance were
WATSON PHARMACEUTICALS, INC. and ABBOTT LABORATORIES. Watson's first quarter
results came in below analyst estimates, and Abbott suffered as it lowered
earnings guidance for the year based on increased operating costs.

Positive performance in the fund was driven by stock selection across most
sub-sectors. Fund holdings in biotechnology company Biogen Idec boosted
performance. Also positively affecting performance was the fund's underweight
position in BRISTOL-MYERS SQUIBB CO. (which the fund no longer holds securities
in) and fund holdings in managed care companies Anthem and WellPoint.


(1)  Lipper, Inc. is a major independent mutual-fund tracking organization.
     Returns are based on the six-month period ended April 30, 2004, calculated
     among the 194 funds in the fund's Lipper category including the
     reinvestment of dividends and capital gains, if any, and excluding sales
     charges.


           2 SMITH BARNEY SECTOR SERIES INC. | 2004 Semi-Annual Report


SPECIAL SHAREHOLDER NOTICE

Effective April 29, 2004, Smith Barney Sector Series on behalf of the Smith
Barney Health Sciences Fund changed its primary performance benchmark from the
Goldman Sachs Healthcare Index to the Russell 3000 Index. The Goldman Sachs
Healthcare Index will continue as a secondary performance benchmark.

INFORMATION ABOUT YOUR FUND

In recent months several issues in the mutual fund industry have come under the
scrutiny of federal and state regulators. The fund's Adviser and some of its
affiliates have received requests for information from various government
regulators regarding market timing, late trading, fees and other mutual fund
issues in connection with various investigations. The regulators appear to be
examining, among other things, the fund's response to market timing and
shareholder exchange activity, including compliance with prospectus disclosure
related to these subjects. The fund has been informed that the Adviser and its
affiliates are responding to those information requests, but are not in a
position to predict the outcome of these requests and investigations.

As always, thank you for your confidence in our stewardship of your assets. We
look forward to helping you continue to meet your financial goals.

Sincerely,

[R. JAY GERKEN SIGNATURE OMITTED]

R. Jay Gerken, CFA
Chairman, President and Chief Executive Officer

MAY 18, 2004



The information provided is not intended to be a forecast of future events, a
guarantee of future results or investment advice. Views expressed may differ
from those of the firm as a whole.

Portfolio holdings and breakdowns are as of April 30, 2004 and are subject to
change and may not be representative of the portfolio manager's current or
future investments. The fund's top ten holdings as of this date were: Johnson &
Johnson (10.6%), Pfizer Inc. (10.4%), Amgen Inc. (6.3%), Eli Lilly & Co. (5.6%),
UnitedHealth Group (4.7%), Abbott Laboratories (4.6%), Genentech, Inc. (4.3%),
Medtronic, Inc. (3.6%), Biogen Idec Inc. (3.6%) and Merck & Co. Inc. (3.5%).
Please refer to page 4 for a list and percentage breakdown of the fund's
holdings.

The mention of sector breakdowns is for informational purposes only and should
not be construed as a recommendation to purchase or sell any securities. The
information provided regarding such sectors is not a sufficient basis upon which
to make an investment decision. Investors seeking financial advice regarding the
appropriateness of investing in any securities or investment strategies
discussed should consult their financial professional. Portfolio holdings are
subject to change at any time and may not be representative of the portfolio
manager's current or future investments. The fund's top four sector holdings as
of April 30, 2004 were: Pharmaceuticals (48.6%); Healthcare Providers and
Services (17.8%); Biotechnology (17.7%); Healthcare Equipment and Supplies
(15.9%). The fund's portfolio composition is subject to change at any time.

RISKS: In addition to normal risks associated with equity investing, narrowly
focused investments typically exhibit higher volatility. The health care sector
may be subject to greater governmental regulation, competitive pressures and
rapid technological change and obsolescence, which may have a materially adverse
effect on the sector. Additionally, the fund's performance will be influenced by
political, social and economic factors affecting investments in companies in
foreign countries. Investing in foreign securities is subject to certain risks
not associated with domestic investing, such as currency fluctuations, and
changes in political and economic conditions. The securities of small- and
mid-sized companies tend to be more volatile than those of larger companies. The
fund may use derivatives, such as options and futures, which can be illiquid,
may disproportionately increase losses, and have a potentially large impact on
fund performance.

All index performance reflects no deduction for fees, expenses or taxes. Please
note that an investor cannot invest directly in an index.

(i)  The Russell 3000 Index measures the performance of the 3,000 largest U.S.
     companies based on total market capitalization, which represent
     approximately 98% of the U.S. equity market.

(ii) The Goldman Sachs Healthcare Index is an unmanaged market-value weighted
     index comprised of healthcare service companies including long-term care
     and hospital facilities, healthcare management organizations and continuing
     care services and pharmaceutical companies.


           3 SMITH BARNEY SECTOR SERIES INC. | 2004 Semi-Annual Report


- --------------------------------------------------------------------------------
 SCHEDULE OF INVESTMENTS (UNAUDITED)                              APRIL 30, 2004
- --------------------------------------------------------------------------------



     SHARES                                                   SECURITY                                                    VALUE
- ------------------------------------------------------------------------------------------------------------------------------------
                                                                                                              
COMMON STOCK  --  100.0%
BIOTECHNOLOGY  --  17.7%
         85,161     Amgen Inc.*                                                                                        $ 4,792,009
         46,390     Biogen Idec Inc.*                                                                                    2,737,010
          8,443     Chiron Corp.*                                                                                          391,755
         26,516     Genentech, Inc.*                                                                                     3,256,165
         41,735     Genzyme Corp.*                                                                                       1,817,977
         21,840     MedImmune, Inc.*                                                                                       529,402
- ------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                        13,524,318
- ------------------------------------------------------------------------------------------------------------------------------------
HEALTHCARE EQUIPMENT AND SUPPLIES  --  15.9%
         10,256     Baxter International, Inc.                                                                             324,602
         14,727     Becton Dickinson & Co.                                                                                 744,450
         53,541     Biomet, Inc.                                                                                         2,114,869
         42,449     Boston Scientific Corp.*                                                                             1,748,474
         19,491     C.R. Bard, Inc.                                                                                      2,071,308
         38,234     Guidant Corp.                                                                                        2,409,124
         55,158     Medtronic, Inc.                                                                                      2,783,273
- ------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                        12,196,100
- ------------------------------------------------------------------------------------------------------------------------------------
HEALTHCARE PROVIDERS AND SERVICES  --  17.8%
          5,700     AmerisourceBergen Corp.                                                                                329,973
         29,186     Anthem, Inc.*                                                                                        2,585,296
         24,052     Cardinal Health, Inc.                                                                                1,761,809
         13,325     CIGNA Corp.                                                                                            859,596
          7,381     HCA Inc.                                                                                               299,890
         35,246     Henry Schein, Inc.*                                                                                  2,483,786
          1,980     Patterson Dental Co.*                                                                                  145,926
         24,700     Tenet Healthcare Corp.*                                                                                290,472
         58,070     UnitedHealth Group Inc.                                                                              3,570,144
         11,656     WellPoint Health Networks, Inc.*                                                                     1,301,859
- ------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                        13,628,751
- ------------------------------------------------------------------------------------------------------------------------------------
PHARMACEUTICALS  --  48.6%
         80,009     Abbott Laboratories                                                                                  3,521,996
         58,424     Eli Lilly & Co.                                                                                      4,312,275
          7,179     Forest Laboratories, Inc.*                                                                             462,902
        149,520     Johnson & Johnson                                                                                    8,078,566
         62,079     Medicis Pharmaceutical Corp., Class A Shares                                                         2,664,431
         56,714     Merck & Co. Inc.                                                                                     2,665,558
        221,648     Pfizer Inc.                                                                                          7,926,132
         56,204     Schering-Plough Corp.                                                                                  940,293
         41,203     Teva Pharmaceutical Industries Ltd., Sponsored ADR                                                   2,536,457
         39,889     Watson Pharmaceuticals, Inc.*                                                                        1,420,447
         68,502     Wyeth                                                                                                2,607,871
- ------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                        37,136,928
- ------------------------------------------------------------------------------------------------------------------------------------
                    TOTAL INVESTMENTS  --  100.0%
                    (Cost  --  $69,427,123**)                                                                          $76,486,097
- ------------------------------------------------------------------------------------------------------------------------------------


 *  NON-INCOME PRODUCING SECURITY.
**  AGGREGATE COST FOR FEDERAL INCOME TAX PURPOSES IS SUBSTANTIALLY THE SAME.

    Abbreviation used in this schedule:
    -----------------------------------
    ADR  --  American Depositary Receipt


                       SEE NOTES TO FINANCIAL STATEMENTS.


           4 SMITH BARNEY SECTOR SERIES INC. | 2004 Semi-Annual Report


- --------------------------------------------------------------------------------
STATEMENT OF ASSETS AND LIABILITIES (UNAUDITED)                   APRIL 30, 2004
- --------------------------------------------------------------------------------



                                                                                                                
ASSETS:
     Investments, at value (Cost  --  $69,427,123)                                                                    $76,486,097
     Receivable for Fund shares sold                                                                                      107,463
     Dividends receivable                                                                                                  27,073
     Prepaid expenses                                                                                                      26,002
- ------------------------------------------------------------------------------------------------------------------------------------
     TOTAL ASSETS                                                                                                      76,646,635
- ------------------------------------------------------------------------------------------------------------------------------------
LIABILITIES:
     Bank overdraft                                                                                                        94,839
     Payable for Fund shares reacquired                                                                                    63,612
     Management fee payable                                                                                                50,674
     Distribution plan fees payable                                                                                        25,275
     Accrued expenses                                                                                                      99,279
- ------------------------------------------------------------------------------------------------------------------------------------
     TOTAL LIABILITIES                                                                                                    333,679
- ------------------------------------------------------------------------------------------------------------------------------------
TOTAL NET ASSETS                                                                                                      $76,312,956
- ------------------------------------------------------------------------------------------------------------------------------------
NET ASSETS:
     Par value of capital shares                                                                                          $ 6,575
     Capital paid in excess of par value                                                                               87,709,705
     Accumulated net investment loss                                                                                     (368,619)
     Accumulated net realized loss from investment transactions and foreign currency transactions                     (18,093,828)
     Net unrealized appreciation of investments and foreign currencies                                                  7,059,123
- ------------------------------------------------------------------------------------------------------------------------------------
TOTAL NET ASSETS                                                                                                      $76,312,956
- ------------------------------------------------------------------------------------------------------------------------------------
SHARES OUTSTANDING:
     Class A                                                                                                            1,809,262
- ------------------------------------------------------------------------------------------------------------------------------------
     Class B                                                                                                            2,860,709
- ------------------------------------------------------------------------------------------------------------------------------------
     Class C                                                                                                            1,904,852
- ------------------------------------------------------------------------------------------------------------------------------------
NET ASSET VALUE:
     Class A (and redemption price)                                                                                        $11.87
- ------------------------------------------------------------------------------------------------------------------------------------
     Class B *                                                                                                             $11.51
- ------------------------------------------------------------------------------------------------------------------------------------
     Class C *                                                                                                             $11.50
- ------------------------------------------------------------------------------------------------------------------------------------
MAXIMUM PUBLIC OFFERING PRICE PER SHARE:
     Class A (net asset value plus 5.26% of net asset value per share)                                                     $12.49
- ------------------------------------------------------------------------------------------------------------------------------------


*  REDEMPTION PRICE IS NAV OF CLASS B AND C SHARES REDUCED BY A 5.00% AND 1.00%
   CONTINGENT DEFERRED SALES CHARGE, RESPECTIVELY, IF SHARES ARE REDEEMED WITHIN
   ONE YEAR FROM PURCHASE PAYMENT (SEE NOTE 2).


                       SEE NOTES TO FINANCIAL STATEMENTS.


           5 SMITH BARNEY SECTOR SERIES INC. | 2004 Semi-Annual Report


- --------------------------------------------------------------------------------
STATEMENT OF OPERATIONS (UNAUDITED)      FOR THE SIX MONTHS ENDED APRIL 30, 2004
- --------------------------------------------------------------------------------



                                                                                                                 
INVESTMENT INCOME:
     Dividends                                                                                                         $  371,249
     Interest                                                                                                               1,270
     Less: Foreign withholding tax                                                                                         (1,369)
- ------------------------------------------------------------------------------------------------------------------------------------
     TOTAL INVESTMENT INCOME                                                                                              371,150
- ------------------------------------------------------------------------------------------------------------------------------------
EXPENSES:
     Management fee (Note 2)                                                                                              302,748
     Distribution plan fees (Note 6)                                                                                      299,016
     Transfer agency services (Note 6)                                                                                     53,926
     Shareholder communications (Note 6)                                                                                   24,738
     Audit and legal                                                                                                       20,808
     Registration fees                                                                                                     15,498
     Custody                                                                                                               10,545
     Directors' fees                                                                                                        4,438
     Other                                                                                                                  6,249
- ------------------------------------------------------------------------------------------------------------------------------------
     TOTAL EXPENSES                                                                                                       737,966
- ------------------------------------------------------------------------------------------------------------------------------------
NET INVESTMENT LOSS                                                                                                      (366,816)
- ------------------------------------------------------------------------------------------------------------------------------------
REALIZED AND UNREALIZED GAIN (LOSS) ON INVESTMENTS
AND FOREIGN CURRENCIES (NOTE 3):
     Realized Gain From:
       Investment transactions                                                                                          3,723,537
       Foreign currency transactions                                                                                          529
- ------------------------------------------------------------------------------------------------------------------------------------
     NET REALIZED GAIN                                                                                                  3,724,066
- ------------------------------------------------------------------------------------------------------------------------------------
     Change in Net Unrealized Appreciation (Depreciation) From:
       Investments                                                                                                      4,220,476
       Foreign currencies                                                                                                    (374)
- ------------------------------------------------------------------------------------------------------------------------------------
     INCREASE IN NET UNREALIZED APPRECIATION                                                                            4,220,102
- ------------------------------------------------------------------------------------------------------------------------------------
NET GAIN ON INVESTMENTS AND FOREIGN CURRENCIES                                                                          7,944,168
- ------------------------------------------------------------------------------------------------------------------------------------
INCREASE IN NET ASSETS FROM OPERATIONS                                                                                 $7,577,352
- ------------------------------------------------------------------------------------------------------------------------------------



                       SEE NOTES TO FINANCIAL STATEMENTS.


           6 SMITH BARNEY SECTOR SERIES INC. | 2004 Semi-Annual Report


- --------------------------------------------------------------------------------
STATEMENTS OF CHANGES IN NET ASSETS
- --------------------------------------------------------------------------------

FOR THE SIX MONTHS ENDED APRIL 30, 2004 (UNAUDITED)
AND THE YEAR ENDED OCTOBER 31, 2003



                                                                                                2004                     2003
- ------------------------------------------------------------------------------------------------------------------------------------
                                                                                                             
OPERATIONS:
     Net investment loss                                                                     $  (366,816)             $  (569,042)
     Net realized gain (loss)                                                                  3,724,066               (8,863,347)
     Increase in net unrealized appreciation                                                   4,220,102               13,129,196
- ------------------------------------------------------------------------------------------------------------------------------------
     INCREASE IN NET ASSETS FROM OPERATIONS                                                    7,577,352                3,696,807
- ------------------------------------------------------------------------------------------------------------------------------------
FUND SHARE TRANSACTIONS (NOTE 8):
     Net proceeds from sale of shares                                                          5,716,390                8,315,118
     Net asset value of shares issued in connection with the transfer of the
       Smith Barney Sector Series Inc. - Biotechnology Fund's net assets (Note 7)                    --                17,667,510
     Cost of shares reacquired                                                               (10,478,339)             (16,121,557)
- ------------------------------------------------------------------------------------------------------------------------------------
     INCREASE (DECREASE) IN NET ASSETS FROM FUND SHARE TRANSACTIONS                           (4,761,949)               9,861,071
- ------------------------------------------------------------------------------------------------------------------------------------
INCREASE IN NET ASSETS                                                                         2,815,403               13,557,878

NET ASSETS:
     Beginning of period                                                                      73,497,553               59,939,675
- ------------------------------------------------------------------------------------------------------------------------------------
     END OF PERIOD*                                                                          $76,312,956              $73,497,553
- ------------------------------------------------------------------------------------------------------------------------------------
* Includes accumulated net investment loss of:                                                 $(368,619)                 $(2,332)
- ------------------------------------------------------------------------------------------------------------------------------------



                       SEE NOTES TO FINANCIAL STATEMENTS.


           7 SMITH BARNEY SECTOR SERIES INC. | 2004 Semi-Annual Report


- --------------------------------------------------------------------------------
NOTES TO FINANCIAL STATEMENTS (UNAUDITED)
- --------------------------------------------------------------------------------

1.  Significant Accounting Policies

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

The following are significant  accounting policies  consistently followed by the
Fund  and  are in  conformity  with  generally  accepted  accounting  principles
("GAAP"):  (a)  security  transactions  are  accounted  for on trade  date;  (b)
securities  traded on  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  sales  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
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, at least  annually;  (i) gains or losses on
the sale of  securities  are  calculated  by using the  specific  identification
method;  (j) class specific expenses are charged to each class;  management fees
and general Fund  expenses are  allocated on the basis of relative net assets of
each class or on another reasonable basis; (k) the character of income and gains
to be distributed is determined in accordance with income tax regulations  which
may differ from U.S.  generally  accepted  accounting  principles;  (l) the Fund
intends to comply with the applicable provisions 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;  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 or offset by entering into another forward
exchange contract. The Fund from time to time may also enter into options and/or
futures contracts typically to hedge market or currency risk.


           8 SMITH BARNEY SECTOR SERIES INC. | 2004 Semi-Annual Report


- --------------------------------------------------------------------------------
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
Fund pays SBFM a  management  fee  calculated  at an annual rate of 0.80% of the
Fund's average daily net assets.  This fee is calculated daily and paid monthly.
SBFM has entered into a sub-advisory  agreement with Citigroup Asset  Management
Ltd. ("CAM Ltd."), an affiliate of SBFM. Pursuant to the sub-advisory agreement,
CAM Ltd. is responsible for the day-to-day  portfolio  operations and investment
decisions  and is  compensated  by SBFM for such  services  at an annual rate of
0.50% of the Fund's average daily net assets.

Citicorp Trust Bank, fsb. ("CTB"), another subsidiary of Citigroup,  acts as the
Fund's transfer agent.  PFPC Inc.  ("PFPC") and Primerica  Shareholder  Services
("PSS"), another subsidiary of Citigroup, act as the Fund's sub-transfer agents.
CTB receives  account fees and asset-based  fees that vary according to the size
and type of account. PFPC and PSS are responsible for shareholder  recordkeeping
and financial  processing for all shareholder  accounts and are paid by CTB. For
the six  months  ended  April 30,  2004,  the Fund paid  transfer  agent fees of
$37,869 to CTB.

Citigroup Global Markets Inc. ("CGM") and PFS Distributors,  Inc., both of which
are subsidiaries of Citigroup, act as the Fund's distributors.

For the six  months  ended  April  30,  2004,  CGM and its  affiliates  received
brokerage commissions of $5,289.

On April 29, 2004, the Fund's Class L shares were renamed as Class C shares.  On
February 2, 2004, initial sales charges on these shares were eliminated.

There is a maximum initial sales charge of 5.00% for Class A shares.  There is a
contingent  deferred  sales  charge  ("CDSC") of 5.00% on Class B shares,  which
applies if redemption  occurs within one year from purchase payment and declines
thereafter by 1.00% per year until no CDSC is incurred. Class C shares also have
a 1.00% CDSC,  which applies if redemption  occurs within one year from purchase
payment.  In  addition,  Class A shares  have a 1.00%  CDSC,  which  applies  if
redemption occurs within one year from purchase payment.  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, 2004, CGM and its  affiliates  received sales
charges of approximately $53,000 and $9,000 on sales of the Fund's Class A and C
shares,  respectively.  In  addition,  for the six months  ended April 30, 2004,
CDSCs paid to CGM and its  affiliates  were  approximately  $44,000  for Class B
shares.

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


3.  Investments

During the six months ended April 30, 2004,  the aggregate cost of purchases and
proceeds  from  sales  of   investments   (including   maturities  of  long-term
investments, but excluding short-term investments) were as follows:

- --------------------------------------------------------------------------------
Purchases                                                            $31,183,101
- --------------------------------------------------------------------------------
Sales                                                                 35,661,204
- --------------------------------------------------------------------------------


           9 SMITH BARNEY SECTOR SERIES INC. | 2004 Semi-Annual Report


- --------------------------------------------------------------------------------
NOTES TO FINANCIAL STATEMENTS (UNAUDITED) (CONTINUED)
- --------------------------------------------------------------------------------

At April 30, 2004, the aggregate gross unrealized  appreciation and depreciation
of investments for Federal income tax purposes were substantially as follows:

- --------------------------------------------------------------------------------
Gross unrealized appreciation                                       $ 9,435,541
Gross unrealized depreciation                                        (2,376,567)
- --------------------------------------------------------------------------------
Net unrealized appreciation                                         $ 7,058,974
- --------------------------------------------------------------------------------


4.  Repurchase Agreements

When  entering  into  repurchase  agreements,  it is the  Fund's  policy  that a
custodian takes possession of the underlying collateral securities, the value of
which at least  equals  the  principal  amount  of the  repurchase  transaction,
including  accrued  interest.  To the  extent  that any  repurchase  transaction
exceeds one business  day, the value of the  collateral is  marked-to-market  to
ensure the adequacy of the  collateral.  If the seller defaults and the value of
the collateral declines or if bankruptcy  proceedings are commenced with respect
to the seller of the security,  realization of the collateral by the Fund may be
delayed or limited.


5.  Concentration of Risk

The  Fund  normally  invests  at  least  80% of its  assets  in  health  related
investments.  As a result of this  concentration  policy, the Fund's investments
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 Rule 12b-1  Distribution  Plan,  the Fund pays a service fee with
respect to its Class A, B and C shares calculated at the annual rate of 0.25% of
the  average  daily net assets of each  respective  class.  The Fund also pays a
distribution  fee with respect to Class B and C shares  calculated at the annual
rate of 0.75% of the average daily net assets of each class,  respectively.  For
the six months ended April 30, 2004,  total Rule 12b-1  Distribution  Plan fees,
which are accrued daily and paid monthly, were as follows:

                                            CLASS A       CLASS B        CLASS C
- --------------------------------------------------------------------------------
Rule 12b-1 Distribution Plan Fees           $26,473      $162,374       $110,169
- --------------------------------------------------------------------------------

For the six months ended April 30, 2004,  total Transfer Agency Service expenses
were as follows:

                                            CLASS A       CLASS B        CLASS C
- --------------------------------------------------------------------------------
Transfer Agency Service Expenses            $15,090       $23,149        $15,687
- --------------------------------------------------------------------------------

For the six  months  ended  April  30,  2004,  total  Shareholder  Communication
expenses were as follows:

                                            CLASS A       CLASS B        CLASS C
- --------------------------------------------------------------------------------
Shareholder Communication Expenses           $6,921       $10,615         $7,202
- --------------------------------------------------------------------------------


7.  Transfer of Net Assets

On May 9, 2003,  the Fund  acquired  the assets and certain  liabilities  of the
Smith  Barney  Sector  Series Inc. -  Biotechnology  Fund  pursuant to a plan of
reorganization  approved by Smith Barney Sector Series Inc. - Biotechnology Fund
shareholders


          10 SMITH BARNEY SECTOR SERIES INC. | 2004 Semi-Annual Report


- --------------------------------------------------------------------------------
NOTES TO FINANCIAL STATEMENTS (UNAUDITED) (CONTINUED)
- --------------------------------------------------------------------------------

on May 7, 2003.  Total  shares  issued by the Fund,  the total net assets of the
Smith Barney Sector Series Inc. - Biotechnology Fund and total net assets of the
Fund on the date of the transfer were as follows:



                                                                                  TOTAL NET ASSETS OF THE SMITH        TOTAL NET
                                                         SHARES ISSUED BY           BARNEY SECTOR SERIES INC. -     ASSETS OF THE
ACQUIRED FUND                                                THE FUND                   BIOTECHNOLOGY FUND               FUND
- ------------------------------------------------------------------------------------------------------------------------------------
                                                                                                            
Smith Barney Sector Series Inc. - Biotechnology Fund         1,588,578                      $16,177,147              $59,712,675
- ------------------------------------------------------------------------------------------------------------------------------------


The total net assets of the Smith Barney Sector Series Inc. - Biotechnology Fund
before   acquisition   included   unrealized   depreciation  of  $1,490,363  and
accumulated  net  realized  loss of  $22,301,542.  Total net  assets of the Fund
immediately after the transfer were $75,889,822.  The transaction was structured
to qualify as a tax-free reorganization under the Internal Revenue Code of 1986,
as amended.


8.  Capital Shares

At April 30, 2004, the Fund had 750 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.  Effective  April 29,
2004, the Fund renamed Class L shares as Class C shares.

Transactions in shares of each class were as follows:



                                                                     SIX MONTHS ENDED                            YEAR ENDED
                                                                      APRIL 30, 2004                          OCTOBER 31, 2003
                                                                --------------------------               ---------------------------
                                                                 SHARES           AMOUNT                  SHARES           AMOUNT
- ------------------------------------------------------------------------------------------------------------------------------------
                                                                                                             
CLASS A
Shares sold                                                      203,466        $2,335,221                369,574        $3,805,312
Net asset value of shares issued in connection with the
  transfer of the Smith Barney Sector Series Inc. -
  Biotechnology Fund's net assets (Note 7)                            --                --                441,379         4,707,530
Shares reacquired                                               (321,475)       (3,666,059)              (534,761)       (5,533,776)
- ------------------------------------------------------------------------------------------------------------------------------------
Net Increase (Decrease)                                         (118,009)      $(1,330,838)               276,192        $2,979,066
- ------------------------------------------------------------------------------------------------------------------------------------
CLASS B
Shares sold                                                      172,943        $1,936,586                338,709        $3,402,113
Net asset value of shares issued in connection with the
  transfer of the Smith Barney Sector Series Inc. -
  Biotechnology Fund's net assets (Note 7)                            --                --                485,123         5,592,990
Shares reacquired                                               (325,670)       (3,609,041)              (532,954)       (5,379,753)
- ------------------------------------------------------------------------------------------------------------------------------------
Net Increase (Decrease)                                         (152,727)      $(1,672,455)               290,878        $3,615,350
- ------------------------------------------------------------------------------------------------------------------------------------
CLASS C+
Shares sold                                                      130,631        $1,444,583                108,563        $1,107,693
Net asset value of shares issued in connection with the
  transfer of the Smith Barney Sector Series Inc. -
  Biotechnology Fund's net assets (Note 7)                            --                --                662,076         7,366,990
Shares reacquired                                               (288,889)       (3,203,239)              (514,940)       (5,208,028)
- ------------------------------------------------------------------------------------------------------------------------------------
Net Increase (Decrease)                                         (158,258)      $(1,758,656)               255,699        $3,266,655
- ------------------------------------------------------------------------------------------------------------------------------------


+  ON APRIL 29, 2004, CLASS L SHARES WERE RENAMED AS CLASS C SHARES.


          11 SMITH BARNEY SECTOR SERIES INC. | 2004 Semi-Annual Report


- --------------------------------------------------------------------------------
NOTES TO FINANCIAL STATEMENTS (UNAUDITED) (CONTINUED)
- --------------------------------------------------------------------------------

9.  Additional Information

The Fund has received the following  information from Citigroup Asset Management
("CAM"),  the  Citigroup  business  unit which  includes  the Fund's  Investment
Manager and other  investment  advisory  companies,  all of which are  indirect,
wholly-owned  subsidiaries of Citigroup.  CAM is reviewing its entry, through an
affiliate,  into the transfer  agent  business in the period  1997-1999.  As CAM
currently  understands  the facts, at the time CAM decided to enter the transfer
agent  business,  CAM  sub-contracted  for a period of five years certain of the
transfer agency services to a third party and also concluded a revenue guarantee
agreement  with this  sub-contractor  providing  that the  sub-contractor  would
guarantee  certain  benefits to CAM or its  affiliates  (the "Revenue  Guarantee
Agreement").  In connection with the subsequent purchase of the sub-contractor's
business by an affiliate of the current  sub-transfer  agent (PFPC Inc.) used by
CAM on many of the  funds it  manages,  this  Revenue  Guarantee  Agreement  was
amended  eliminating those benefits in exchange for arrangements that included a
one-time payment from the sub-contractor.

The Boards of CAM-managed  funds (the "Boards") were not informed of the Revenue
Guarantee  Agreement with the  sub-contractor  at the time the Boards considered
and approved the transfer agent  arrangements.  Nor were the Boards  informed of
the subsequent amendment to the Revenue Guarantee Agreement when that occurred.

CAM has begun to take corrective  actions.  CAM will pay to the applicable funds
approximately  $17 million (plus interest) that CAM and its affiliates  received
from the  Revenue  Guarantee  Agreement  and its  amendment.  CAM also  plans an
independent  review to verify that the transfer  agency fees charged by CAM were
fairly priced as compared to competitive  alternatives.  CAM is instituting  new
procedures and making  changes  designed to ensure no similar  arrangements  are
entered into in the future.

CAM has  briefed  the  SEC,  the New  York  State  Attorney  General  and  other
regulators  with  respect to this  matter,  as well as the U.S.  Attorney who is
investigating the matter.  CAM is cooperating with  governmental  authorities on
this matter, the ultimate outcome of which is not yet determinable.


10. Legal Matters

Class action lawsuits have been filed against Citigroup Global Markets Inc. (the
"Distributor")  and a number of its  affiliates,  including  Smith  Barney  Fund
Management  LLC and Salomon  Brothers  Asset  Management  Inc (the  "Advisers"),
substantially all of the mutual funds managed by the Advisers (the "Funds"), and
directors or trustees of the Funds. The complaints  allege,  among other things,
that the Distributor created various  undisclosed  incentives for its brokers to
sell Smith Barney and Salomon  Brothers  funds.  In  addition,  according to the
complaints, the Advisers caused the Funds to pay excessive brokerage commissions
to  the  Distributor  for  steering  clients  towards   proprietary  funds.  The
complaints also allege that the defendants  breached their fiduciary duty to the
Funds by  improperly  charging  Rule 12b-1 fees and by drawing on Fund assets to
make undisclosed  payments of soft dollars and excessive brokerage  commissions.
The complaints seek injunctive  relief and  compensatory  and punitive  damages,
rescission of the Funds' contracts with the Advisers,  recovery of all fees paid
to the Advisers  pursuant to such contracts and an award of attorneys'  fees and
litigation  expenses.  Citigroup  Asset  Management  believes that the suits are
without merit and intends to defend the cases vigorously.

Additional  lawsuits arising out of these  circumstances and presenting  similar
allegations  and requests for relief may be filed against the  defendants in the
future. Neither Citigroup Asset Management nor the Funds believe that any of the
pending actions will have a material  adverse effect on the Funds or the ability
of the Distributor or the Advisers to perform under their  respective  contracts
with the Funds.


          12 SMITH BARNEY SECTOR SERIES INC. | 2004 Semi-Annual Report


- --------------------------------------------------------------------------------
FINANCIAL HIGHLIGHTS
- --------------------------------------------------------------------------------

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



CLASS A SHARES                                         2004(1)(2)       2003(2)          2002(2)           2001             2000(3)
- ------------------------------------------------------------------------------------------------------------------------------------
                                                                                                           
NET ASSET VALUE, BEGINNING OF PERIOD                  $10.71           $ 9.84           $12.72            $14.49           $11.40
- ------------------------------------------------------------------------------------------------------------------------------------
INCOME (LOSS) FROM OPERATIONS:
   Net investment loss(4)                              (0.02)           (0.03)           (0.07)            (0.08)           (0.04)
   Net realized and unrealized gain (loss)              1.18             0.90            (2.64)            (1.29)            3.13
- ------------------------------------------------------------------------------------------------------------------------------------
Total Income (Loss) From Operations                     1.16             0.87            (2.71)            (1.37)            3.09
- ------------------------------------------------------------------------------------------------------------------------------------
LESS DISTRIBUTIONS FROM:
   Net realized gains                                     --               --            (0.17)            (0.40)              --
- ------------------------------------------------------------------------------------------------------------------------------------
Total Distributions                                       --               --            (0.17)            (0.40)              --
- ------------------------------------------------------------------------------------------------------------------------------------
NET ASSET VALUE, END OF PERIOD                        $11.87           $10.71          $  9.84            $12.72           $14.49
- ------------------------------------------------------------------------------------------------------------------------------------
TOTAL RETURN(5)                                        10.83%++          8.84%          (21.65)%           (9.83)%          27.11%++
- ------------------------------------------------------------------------------------------------------------------------------------
NET ASSETS, END OF PERIOD (000s)                     $21,484          $20,636          $16,251           $19,806          $16,980
- ------------------------------------------------------------------------------------------------------------------------------------
RATIOS TO AVERAGE NET ASSETS:
   Expenses(4)(6)                                       1.41%+           1.35%            1.49%             1.50%            1.52%+
   Net investment loss                                 (0.42)+          (0.30)           (0.58)            (0.63)           (0.67)+
- ------------------------------------------------------------------------------------------------------------------------------------
PORTFOLIO TURNOVER RATE                                   41%              68%              26%               34%              26%
- ------------------------------------------------------------------------------------------------------------------------------------

CLASS B SHARES                                         2004(1)(2)       2003(2)          2002(2)           2001             2000(3)
- ------------------------------------------------------------------------------------------------------------------------------------
NET ASSET VALUE, BEGINNING OF PERIOD                  $10.41           $ 9.64           $12.56            $14.42           $11.40
- ------------------------------------------------------------------------------------------------------------------------------------
INCOME (LOSS) FROM OPERATIONS:
   Net investment loss(4)                              (0.07)           (0.11)           (0.15)            (0.18)           (0.09)
   Net realized and unrealized gain (loss)              1.17             0.88            (2.60)            (1.28)            3.11
- ------------------------------------------------------------------------------------------------------------------------------------
Total Income (Loss) From Operations                     1.10             0.77            (2.75)            (1.46)            3.02
- ------------------------------------------------------------------------------------------------------------------------------------
LESS DISTRIBUTIONS FROM:
   Net realized gains                                     --               --            (0.17)            (0.40)              --
- ------------------------------------------------------------------------------------------------------------------------------------
Total Distributions                                       --               --            (0.17)            (0.40)              --
- ------------------------------------------------------------------------------------------------------------------------------------
NET ASSET VALUE, END OF PERIOD                        $11.51           $10.41          $  9.64            $12.56           $14.42
- ------------------------------------------------------------------------------------------------------------------------------------
TOTAL RETURN(5)                                        10.57%++          7.99%          (22.25)%          (10.51)%          26.49%++
- ------------------------------------------------------------------------------------------------------------------------------------
NET ASSETS, END OF PERIOD (000s)                     $32,914          $31,380          $26,258           $34,146          $28,694
- ------------------------------------------------------------------------------------------------------------------------------------
RATIOS TO AVERAGE NET ASSETS:
   Expenses(4)(7)                                       2.16%+           2.11%            2.24%             2.25%            2.26%+
   Net investment loss                                 (1.18)+          (1.05)           (1.33)            (1.38)           (1.41)+
- ------------------------------------------------------------------------------------------------------------------------------------
PORTFOLIO TURNOVER RATE                                   41%              68%              26%               34%              26%
- ------------------------------------------------------------------------------------------------------------------------------------


(1) FOR THE SIX MONTHS ENDED APRIL 30, 2004 (UNAUDITED).

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

(3) FOR THE PERIOD FEBRUARY 28, 2000 (INCEPTION DATE) TO OCTOBER 31, 2000.

(4) THE MANAGER WAIVED A PORTION OF ITS FEES FOR THE YEAR ENDED OCTOBER 31, 2001
    AND FOR 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 Waivers
                           -----------------------      -----------------------
                           2001              2000       2001              2000
                           -----             -----      -----             -----
    Class A Shares         $0.01             $0.00*      1.53%            1.94%+
    Class B Shares          0.00*             0.01       2.28             2.68+

(5) PERFORMANCE  FIGURES MAY REFLECT FEE WAIVERS AND/OR EXPENSE  REIMBURSEMENTS.
    PAST  PERFORMANCE IS NO GUARANTEE OF FUTURE  RESULTS.  IN THE ABSENCE OF FEE
    WAIVERS AND/OR EXPENSE REIMBURSEMENTS, THE TOTAL RETURN WOULD BE REDUCED.

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

(7) AS A RESULT OF  VOLUNTARY  EXPENSE  LIMITATIONS,  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.


          13 SMITH BARNEY SECTOR SERIES INC. | 2004 Semi-Annual Report


- --------------------------------------------------------------------------------
FINANCIAL HIGHLIGHTS (CONTINUED)
- --------------------------------------------------------------------------------

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



CLASS C SHARES(1)                                      2004(2)(3)       2003(3)          2002(3)           2001             2000(4)
- ------------------------------------------------------------------------------------------------------------------------------------
                                                                                                           
NET ASSET VALUE, BEGINNING OF PERIOD                  $10.41           $ 9.64           $12.56            $14.42           $11.40
- ------------------------------------------------------------------------------------------------------------------------------------
INCOME (LOSS) FROM OPERATIONS:
   Net investment loss(5)                              (0.07)           (0.11)           (0.15)            (0.18)           (0.09)
   Net realized and unrealized gain (loss)              1.16             0.88            (2.60)            (1.28)            3.11
- ------------------------------------------------------------------------------------------------------------------------------------
Total Income (Loss) From Operations                     1.09             0.77            (2.75)            (1.46)            3.02
- ------------------------------------------------------------------------------------------------------------------------------------
LESS DISTRIBUTIONS FROM:
   Net realized gains                                     --               --            (0.17)            (0.40)              --
- ------------------------------------------------------------------------------------------------------------------------------------
Total Distributions                                       --               --            (0.17)            (0.40)              --
- ------------------------------------------------------------------------------------------------------------------------------------
NET ASSET VALUE, END OF PERIOD                        $11.50           $10.41           $ 9.64            $12.56           $14.42
- ------------------------------------------------------------------------------------------------------------------------------------
TOTAL RETURN(6)                                        10.47%++          7.99%          (22.25)%          (10.51)%          26.49%++
- ------------------------------------------------------------------------------------------------------------------------------------
NET ASSETS, END OF PERIOD (000s)                     $21,915          $21,482          $17,431           $26,932          $26,273
- ------------------------------------------------------------------------------------------------------------------------------------
RATIOS TO AVERAGE NET ASSETS:
   Expenses(5)(7)                                       2.16%+           2.10%            2.24%             2.25%            2.27%+
   Net investment loss                                 (1.18)+          (1.05)           (1.33)            (1.37)           (1.42)+
- ------------------------------------------------------------------------------------------------------------------------------------
PORTFOLIO TURNOVER RATE                                   41%              68%              26%               34%              26%
- ------------------------------------------------------------------------------------------------------------------------------------


(1) ON APRIL 29, 2004, CLASS L SHARES WERE RENAMED AS CLASS C SHARES.

(2) FOR THE SIX MONTHS ENDED APRIL 30, 2004 (UNAUDITED).

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

(4) FOR THE PERIOD FEBRUARY 28, 2000 (INCEPTION DATE) TO OCTOBER 31, 2000.

(5) THE MANAGER WAIVED A PORTION OF ITS FEES FOR THE YEAR ENDED OCTOBER 31, 2001
    AND FOR 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
                            -----------------------     -----------------------
                            2001              2000      2001              2000
                            -----             -----     -----             -----
    Class C Shares          $0.00*            $0.01     2.28%             2.68%+

(6) PERFORMANCE  FIGURES MAY REFLECT FEE WAIVERS AND/OR EXPENSE  REIMBURSEMENTS.
    PAST  PERFORMANCE IS NO GUARANTEE OF FUTURE  RESULTS.  IN THE ABSENCE OF FEE
    WAIVERS AND/OR EXPENSE REIMBURSEMENTS, THE TOTAL RETURN WOULD BE REDUCED.

(7) AS A RESULT OF  VOLUNTARY  EXPENSE  LIMITATIONS,  THE RATIO OF  EXPENSES  TO
    AVERAGE NET ASSETS WILL NOT EXCEED 2.25% FOR CLASS C 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.


          14 SMITH BARNEY SECTOR SERIES INC. | 2004 Semi-Annual Report



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                      (This page intentionally left blank.)




SMITH BARNEY
HEALTH SCIENCES FUND



                DIRECTORS                       INVESTMENT MANAGER
                Dwight B. Crane                 Smith Barney Fund Management LLC
                Burt N. Dorsett
                R. Jay Gerken, CFA              DISTRIBUTORS
                  CHAIRMAN                      Citigroup Global Markets Inc.
                Elliot S. Jaffe                 PFS Distributors, Inc.
                Stephen E. Kaufman
                Joseph J. McCann                CUSTODIAN
                Cornelius C. Rose, Jr.          State Street Bank and
                                                  Trust Company
                OFFICERS
                R. Jay Gerken, CFA              TRANSFER AGENT
                President and Chief             Citicorp Trust Bank, fsb.
                Executive Officer               125 Broad Street, 11th Floor
                                                New York, New York 10004
                Andrew B. Shoup
                Senior Vice President and       SUB-TRANSFER AGENTS
                Chief Administrative Officer    PFPC Inc.
                                                P.O. Box 9699
                Andrew Beagley                  Providence, Rhode Island
                Chief Anti-Money                02940-9699
                Laundering Compliance
                Officer
                                                Primerica Shareholder Services
                Kaprel Ozsolak                  P.O. Box 9662
                Controller                      Providence, Rhode Island
                                                02940-9662
                Robert I. Frenkel
                Secretary and
                Chief Legal Officer




SMITH BARNEY SECTOR SERIES INC.
- --------------------------------------------------------------------------------

SMITH BARNEY HEALTH SCIENCES FUND

The Fund is a separate investment fund of the Smith Barney Sector Series Inc., a
Maryland corporation.





A description of the policies and procedures that the Fund uses to determine how
to vote proxies relating to portfolio securities is available without charge,
upon request, by telephoning the Fund (toll-free) at 1-800-451-2010 and by
visiting the SEC's web site at www.sec.gov.



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.


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


THIS DOCUMENT MUST BE PRECEDED OR ACCOMPANIED BY A FREE PROSPECTUS. INVESTORS
SHOULD CONSIDER THE FUND'S INVESTMENT OBJECTIVES, RISKS, CHARGES AND EXPENSES
CAREFULLY BEFORE INVESTING. THIS PROSPECTUS CONTAINS THIS AND OTHER IMPORTANT
INFORMATION ABOUT THE FUND. PLEASE READ THE PROSPECTUS CAREFULLY BEFORE YOU
INVEST OR SEND MONEY.


www.smithbarneymutualfunds.com





(C)2004 Citigroup Global Markets Inc.
Member NASD, SIPC

FD02553 6/04                                                             04-6750




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- 3(c) under the
              Investment Company Act of 1940, as amended (the "1940 Act")) are
              effective as of a date within 90 days of the filing date of this
              report that includes the disclosure required by this paragraph,
              based on their evaluation of the disclosure controls and
              procedures required by Rule 30a-3(b) under the 1940 Act and
              15d-15(b) under the Securities Exchange Act of 1934.

         (b)  There were no changes in the registrant's internal control over
              financial reporting (as defined in Rule 30a-3(d) under the 1940
              Act) that occurred during the registrant's last fiscal half-year
              (the registrant's second fiscal half-year in the case of an annual
              report) that have materially affected, or are likely to materially
              affect the registrant's internal control over financial reporting.

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 7, 2004

     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 7, 2004

By:  /s/ Andrew B. Shoup
     -------------------
         Andrew B. Shoup
         Chief Administrative Officer of
         Smith Barney Sector Series Inc.

Date:    July 7, 2004