Legg Mason Partners Sector Series N-CSRS Certified semi-annual shareholder report (management investment company)

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, 2005

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, 2005

Your Serious Money. Professionally Managed.^® is a registered service mark of Citigroup Global Markets Inc.

N O T   F D I C   I N S U R E D   •   N O T   B A N K   G U A R A N T E E D   •   M A Y   L O S E   V A L U E

 Research Series

Semi-Annual Report • April 30, 2005

SMITH BARNEY
HEALTH SCIENCES FUND

SMITH BARNEY FUND MANAGEMENT LLCSmith Barney Fund Management LLC is the investment manager to the Fund. Citigroup Asset Management Ltd. 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. * 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.
	What’s Inside
	Letter from the Chairman  Fund at a Glance  Fund Expenses  Schedule of Investments  Statement of Assets and Liabilities  Statement of Operations  Statements of Changes in Net Assets  Financial Highlights  Notes to Financial Statements	1 4 5 7 9 10 11 12 14

L E T T E R   F R O M   T H E   C H A I R M A N

Dear Shareholder, Despite rising interest rates, climbing oil prices, geopolitical concerns and uncertainties surrounding the U.S. Presidential election, the U.S. economy continued to expand during the period. Following a robust 4.0% gain in the third quarter of 2004, gross domestic product (“GDP”)i growth was 3.8% in the fourth quarter. After the end of the Fund’s reporting period, the advance first quarter GDP figure was revised up to 3.5% from 3.1%. Given the overall strength of the economy, the Federal Reserve Board (“Fed”)ii continued to raise interest rates over the period in an attempt to ward off inflation. Following three 25 basis pointiii rate hikes from June through September 2004, the Fed again increased its target for the federal funds rateiv in 0.25% increments four times during the reporting period. After the Fund’s reporting period had ended, at its May meeting, the Fed once again raised its federal funds target rate by 0.25% to 3.00% . During the six months covered by this report, the U.S. stock market posted a modest gain, with the S&P 500 Indexv returning 3.28% . The reporting period began on a bright note, as the equity markets rallied sharply in November and December 2004. Investors were drawn to stocks as the uncertainty of the U.S. Presidential election ended and oil prices fell from their record highs.Thus far in 2005, the equity markets have been volatile. Equities were weak in January, rose in February and again fell in March and April.The market’s recent troubles have been attributed to mixed economic data, continued high oil prices, and rising interest rates.

R. JAY GERKEN, CFA Chairman, President and Chief Executive Officer

Looking at the reporting perisod as a whole, the trend of value-oriented stocks outperforming their growth counterparts continued. In addition, mid- and large-cap stocks generally outperformed their small-cap brethren during the period. Performance Review For the six months ended April 30, 2005, Class A shares of the Smith Barney Sector Series Inc.—Smith Barney Health Sciences Fund, excluding sales charges, returned 15.18% . These shares outperformed the Fund’s unmanaged benchmarks, the Russell 3000 Indexvi and the Goldman Sachs Healthcare Index,vii which returned 3.69% and 13.63%, respectively, for the same period. The Lipper Health/Biotechnology Funds Category Average1 was 5.98% over the same time frame.

¹      Lipper, Inc. is a major independent mutual-fund tracking organization. Returns are based on the six-month period ended April 30, 2005 including the reinvestment of dividends and capital gains distributions, if any, calculated among the 183 funds in the Fund’s Lipper category, and excluding sales charges.

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PERFORMANCE SNAPSHOT AS OF APRIL 30, 2005 (excluding sales charges) (unaudited)

	6 Months
Smith Barney Health Sciences Fund — Class A Shares	15.18	%
Russell 3000 Index	3.69	%
Goldman Sachs Healthcare Index	13.63	%
Lipper Health/Biotechnology Funds Category Average	5.98	%

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. 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.citigroupam.com.

Current reimbursements and/or fee waivers are voluntary, and may be reduced or terminated at any time. Absent these reimbursements or waivers, performance would have been lower.

Class A share returns assume the reinvestment of all 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 14.78% and Class C shares returned 14.89% over the six months ended April 30, 2005.

Information About Your Fund

As you may be aware, several issues in the mutual fund industry have recently 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.

Important information concerning the Fund and its Adviser with regard to recent regulatory developments is contained in the “Additional Information” note in the Notes to the Financial Statements included in this report.

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

R. Jay Gerken, CFA

Chairman, President and Chief Executive Officer

May 17, 2005

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.

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. The securities of small- and mid-cap 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. Please see the Fund’s prospectus for more information on these and other risks.

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

i	Gross domestic product is a market value of goods and services produced by labor and property in a given country.
ii	The Federal Reserve Board is responsible for the formulation of a policy designed to promote economic growth, full employment, stable prices, and a sustainable pattern of international trade and payments.
iii	A basis point is one one-hundredth (1/100 or 0.01) of one percent.
iv	The federal funds rate is the interest rate that banks with excess reserves at a Federal Reserve district bank charge other banks that need overnight loans.
v	The S&P 500 Index is a market capitalization-weighted index of 500 widely held common stocks.
vi	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.
vii	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.

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Fund at a Glance (unaudited)Investment Breakdown

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Fund Expenses (unaudited)

Example

As a shareholder of the Fund, you may incur two types of costs: (1) transaction costs, including front-end and back-end sales charges (loads) on purchase payments, reinvested dividends, or other distributions; and (2) ongoing costs, including management fees; distribution and/or service (12b-1) fees; and other Fund expenses.This example is intended to help you understand your ongoing costs (in dollars) of investing in the Fund and to compare these costs with the ongoing costs of investing in other mutual funds.

This example is based on an investment of $1,000 invested on November 1, 2004 and held for the six months ended April 30, 2005.

Actual Expenses

The table below titled “Based on Actual Total Return” provides information about actual account values and actual expenses. You may use the information provided in this table, together with the amount you invested, to estimate the expenses that you paid over the period. To estimate the expenses you paid on your account, divide your ending account value by $1,000 (for example, an $8,600 ending account value divided by $1,000 = 8.6), then multiply the result by the number under the heading entitled “Expenses Paid During the Period”.

Based on Actual Total Return⁽¹⁾

	Actual Total Return Without Sales Charges(2)
				Beginning		Ending	Annualized Expense Ratio			Expenses
				Account		Account				Paid During
				Value		Value				the Period(3)
Class A	15.18	%	$	1,000.00	$	1,151.80	1.50	%	$	8.00
Class B	14.78			1,000.00		1,147.80	2.25			11.98
Class C	14.89			1,000.00		1,148.90	2.24			11.93

(1)	For the six months ended April 30, 2005.
(2)	Assumes reinvestment of all dividends and capital gain distributions, if any, at net asset value and does not reflect the deduction of the applicable sales charge with respect to Class A shares or the applicable contingent deferred sales charges (“CDSC”) with respect to Class B and C shares. Total return is not annualized, as it may not be representative of the total return for the year. Performance figures may reflect voluntary fee waivers and/or expense reimbursements. In the absence of voluntary fee waivers and/or expense reimbursements, the total return would have been lower.
(3)	Expenses (net of voluntary expense reimbursements) are equal to each class’ respective annualized expense ratio multiplied by the average account value over the period, multiplied by the number of days in the most recent fiscal half-year, then divided by 365.

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Fund Expenses (unaudited) (continued)

Hypothetical Example for Comparison Purposes

The table below titled “Based on Hypothetical Total Return” provides information about hypothetical account values and hypothetical expenses based on the actual expense ratio and an assumed rate of return of 5.00% per year before expenses, which is not the Fund’s actual return.The hypothetical account values and expenses may not be used to estimate the actual ending account balance or expenses you paid for the period.You may use the information provided in this table to compare the ongoing costs of investing in the Fund and other funds.To do so, compare the 5.00% hypothetical example relating to the Fund with the 5.00% hypothetical examples that appear in the shareholder reports of the other funds.

Please note that the expenses shown in the table below are meant to highlight your ongoing costs only and do not reflect any transactional costs, such as front-end or back-end sales charges (loads).Therefore, the table is useful in comparing ongoing costs only, and will not help you determine the relative total costs of owning different funds. In addition, if these transaction costs were included, your costs would have been higher.

Based on Hypothetical Total Return⁽¹⁾

	Hypothetical Annualized Total Return			Beginning		Ending	Annualized Expense Ratio			Expenses
				Account		Account				Paid During
				Value		Value				the Period(2)
Class A	5.00	%	$	1,000.00	$	1,017.36	1.50	%	$	7.50
Class B	5.00			1,000.00		1,013.64	2.25			11.23
Class C	5.00			1,000.00		1,013.69	2.24			11.18

(1)	For the six months ended April 30, 2005.
(2)	Expenses (net of voluntary expense reimbursements) are equal to each class’ respective annualized expense ratio multiplied by the average account value over the period, multiplied by the number of days in the recent fiscal half-year, then divided by 365.

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Schedule of Investments (unaudited)			April 30, 2005
SHARES		SECURITY		VALUE
COMMON STOCK — 99.7%
Biotechnology—	10.3%
28,929		Amgen Inc. (a)	$	1,683,957
5,437		Biogen Idec Inc. (a)		197,037
65,824		Genentech, Inc. (a)		4,669,555
9,842		Genzyme Corp. (a)		576,840
				7,127,389
Healthcare Equipment & Supplies — 9.5%
23,619		Biomet, Inc.		913,819
42,449		Boston Scientific Corp. (a)		1,255,641
12,680		C.R. Bard, Inc.		902,436
29,234		Medtronic, Inc.		1,540,632
38,536		Smith & Nephew PLC, Sponsored ADR		1,981,136
				6,593,664
Healthcare Providers & Services — 25.4%
13,986		Aetna Inc.		1,026,153
43,544		AmerisourceBergen Corp.		2,668,376
24,052		Cardinal Health, Inc.		1,336,570
27,226		CIGNA Corp.		2,504,247
60,115		McKesson Corp.		2,224,255
57,128		Triad Hospitals, Inc. (a)		2,927,810
15,518		UnitedHealth Group Inc.		1,466,606
14,665		Universal Health Services, Inc., Class B Shares		832,092
20,908		WellPoint Inc. (a)		2,670,997
				17,657,106
Pharmaceuticals — 54.5%
105,379		Abbott Laboratories		5,180,432
78,541		Eli Lilly & Co.		4,592,292
38,695		Forest Laboratories, Inc. (a)		1,380,638
107,133		Johnson & Johnson		7,352,538
62,079		Medicis Pharmaceutical Corp., Class A Shares		1,744,420
110,024		Merck & Co., Inc.		3,729,814
94,515		Pfizer Inc.		2,567,972
143,438		Schering-Plough Corp.		2,993,551
50,231		Teva Pharmaceutical Industries Ltd., Sponsored ADR		1,569,216
39,889		Watson Pharmaceuticals, Inc. (a)		1,196,670
122,060		Wyeth		5,485,376
				37,792,919
		TOTAL COMMON STOCK — 99.7% (Cost — $62,980,253)		69,171,078

See Notes to Financial Statements.

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Schedule of Investments (unaudited) (continued)			April 30, 2005
	FACE AMOUNT
		SECURITY		VALUE
REPURCHASE AGREEMENT — 0.5%
$	329,000	State Street Bank & Trust Co., dated 4/29/05, 2.600% due 5/2/05;
		7.250% due 8/15/22; Market value — $340,408) (Cost — $329,000)
		7.250% due 8/15/22; Market value — $340,408) (Cost — $329,000)	$	329,000
		TOTAL INVESTMENTS — 100.2% (Cost — $63,309,253*)		69,500,078
		Liabilities in Excess of Other Assets — (0.2%)		(112,500	)
		TOTAL NET ASSETS — 100.0%	$	69,387,578

(a)	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.

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Statement of Assets and Liabilities (unaudited)	April 30, 2005
ASSETS:
Investments, at value (Cost — $63,309,253)	$	69,500,078
Cash		783
Receivable for Fund shares sold		45,717
Dividends and interest receivable		41,990
Prepaid expenses		21,575
Total Assets		69,610,143
LIABILITIES:
Payable for Fund shares reacquired		90,641
Management fee payable		43,584
Transfer agency services payable		18,143
Distribution plan fees payable		12,941
Directors’ fees payable		8,640
Accrued expenses		48,616
Total Liabilities	$	222,565
Total Net Assets	$	69,387,578
NET ASSETS:
Par value of capital shares (Note 5)	$	5,589
Capital paid in excess of par value		75,899,723
Accumulated net investment loss		(252,184	)
Accumulated net realized loss from investment transactions		(12,456,375	)
Net unrealized appreciation on investments		6,190,825
Total Net Assets	$	69,387,578
Shares Outstanding:
Class A		1,704,901
Class B		2,396,580
Class C		1,487,665
Net Asset Value:
Class A (and redemption price)	$	12.75
Class B *	$	12.27
Class C *	$	12.27
Maximum Public Offering Price Per Share:
Class A (based on a maximum sales charge of 5.00%)	$	13.42

*      Redemption price is NAV of Class B and C shares reduced by a 5.00% and 1.00% CDSC, respectively, if shares are redeemed within one year from purchase payment (See Note 2).

See Notes to Financial Statements.

9 Smith Barney Sector Series Inc. | 2005 Semi-Annual Report

Statement of Operations (unaudited)	For the Six Months Ended April 30, 2005
INVESTMENT INCOME:
Dividends		$	427,532
Interest	208
Less: Foreign withholding tax	(1,820			)
Total Investment Income	425,920
EXPENSES:
Management fee (Note 2)	268,431
Distribution plan fees (Notes 2 and 4)	259,418
Transfer agency services (Notes 2 and 4)	67,937
Shareholder communications (Note 4)	30,001
Registration fees	18,844
Audit and legal	18,297
Custody	9,521
Directors’ fees	8,927
Other	4,715
Total Expenses	686,091
Less: Expense reimbursements (Note 2)	(8,471			)
Net Expenses	677,620
Net Investment Loss	(251,700			)
REALIZED AND UNREALIZED GAIN ON INVESTMENTS (NOTES 1 AND 3)
Net realized gain from investment transactions	3,707,110
Net change in unrealized appreciation/depreciation of investments	5,964,129
Net Gain on Investments	9,671,239
Increase in Net Assets From Operations		$	9,419,539

See Notes to Financial Statements.

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Statements of Changes in Net Assets
For the Six Months Ended April 30, 2005 (unaudited)  and the Year Ended October 31, 2004		2005			2004
OPERATIONS:
Net investment loss	$	(251,700	)	$	(671,592	)
Net realized gain		3,707,110			5,654,582
Net change in unrealized appreciation/depreciation		5,964,129			(2,612,325	)
Increase in Net Assets From Operations		9,419,539			2,370,665
FUND SHARE TRANSACTIONS (NOTE 5):
Net proceeds from sales of shares		4,142,159			8,694,811
Cost of shares reacquired		(10,276,959	)		(18,460,190	)
Decrease in Net Assets From Fund Share Transactions		(6,134,800	)		(9,765,379	)
Increase (Decrease) in Net Assets		3,284,739			(7,394,714	)
NET ASSETS:
Beginning of period		66,102,839			73,497,553
End of period*	$	69,387,578		$	66,102,839
* Includes accumulated net investment loss of:	$	(252,184	)	$	(484	)

See Notes to Financial Statements.

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Financial HighlightsFor a share of each class of capital stock outstanding throughout each year or period ended October 31, unless otherwise noted:

Class A Shares	2005	(1)(2)	2004	(2)		2003	(2)		2002	(2)	2001		2000	(3)
Net Asset Value, Beginning of Period	$11.07		$10.71		$	9.84			$12.72		$14.49		$11.40
Income (Loss) From Operations:
Net investment loss	(0.01	)	(0.04	)		(0.03	)		(0.07	)	(0.08	)	(0.04	)
Net realized and unrealized gain (loss)	1.69		0.40			0.90			(2.64	)	(1.29	)	3.13
Total Income (Loss) From Operations	1.68		0.36			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	$12.75		$11.07			$10.71		$	9.84		$12.72		$14.49
Total Return(4)	15.18	%‡	3.36	%		8.84	%		(21.65	)%	(9.83	)%	27.11	%‡
Net Assets, End of Period (000s)	$21,745		$19,346			$20,636			$16,251		$19,806		$16,980
Ratios to Average Net Assets:
Expenses(5)	1.50%(6)†		1.42%(6)			1.35	%		1.49	%	1.50%(6)		1.52	%(6)†
Net investment loss	(0.24	)†	(0.38	)		(0.30	)		(0.58	)	(0.63	)	(0.67	)†
Portfolio Turnover Rate	15	%	65	%		68	%		26	%	34	%	26	%
Class B Shares	2005	(1)(2)	2004	(2)		2003	(2)		2002	(2)	2001		2000	(3)
Net Asset Value, Beginning of Period	$10.69		$ 10.41			$9.64			$12.56		$14.42		$11.40
Income (Loss) From Operations:
Net investment loss	(0.06	)	(0.13	)		(0.11	)		(0.15	)	(0.18	)	(0.09	)
Net realized and unrealized gain (loss)	1.64		0.41			0.88			(2.60	)	(1.28	)	3.11
Total Income (Loss) From Operations	1.58		0.28			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	$12.27		$10.69			$10.41		$	9.64		$12.56		$14.42
Total Return(4)	14.78	%‡	2.69	%		7.99	%		(22.25	)%	(10.51	)%	26.49	%‡
Net Assets, End of Period (000s)	$29,396		$28,452			$31,380			$26,258		$34,146		$28,694
Ratios to Average Net Assets:
Expenses(5)	2.25	%†(6)	2.17	%(6)		2.11	%		2.24	%	2.25	%(6)	2.26	%(6)†
Net investment loss	(0.98	)†	(1.13	)		(1.05	)		(1.33	)	(1.38	)	(1.41	)†
Portfolio Turnover Rate	15	%	65	%		68	%		26	%	34	%	26	%

(1	)	For the six months ended April 30, 2005 (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	)	Performance figures may reflect voluntary fee waivers and/or expense reimbursements. Past performance is no guarantee of future results. In the absence of voluntary fee waivers and/or expense reimbursements, the total return would have been lower.
(5	)	As a result of voluntary expense limitations, the ratio of expenses to average net assets will not exceed 1.50% for Class A shares and 2.25% for Class B shares.
(6	)	The investment manager voluntarily waived a portion of its fees and/or reimbursed expenses for the period ended April 30, 2005, years ended October 31, 2004, 2001 and for the period ended October 31, 2000. If such fees were not voluntarily waived and/or expenses not reimbursed, the expense ratios would have been 1.56% (annualized), 1.46%, 1.53%, and 1.94% (annualized), respectively, for Class A shares and 2.27 annualized), 2.21%, 2.28%, and 2.68% (annualized), respectively, for Class B shares.
‡		Total return is not annualized, as it may not be representative of the total return for the year.
†		Annualized.

See Notes to Financial Statements.

12 Smith Barney Sector Series Inc. | 2005 Semi-Annual Report

Financial Highlights (continued)
For a share of each class of capital stock outstanding throughout each year or period ended October 31, unless otherwise noted:

Class C Shares(1)	2005	(2)(3)	2004	(3)		2003	(3)		2002	(3)	2001		2000	(4)
Net Asset Value, Beginning of Period	$ 10.68		$ 10.41		$	9.64			$ 12.56		14.42		$ 11.40
Income (Loss) From Operations:
Net investment loss	(0.05	)	(0.12	)		(0.11	)		(0.15	)	(0.18	)	(0.09	)
Net realized and unrealized gain (loss)	1.64		0.39			0.88			(2.60	)	(1.28	)	3.11
Total Income (Loss) From Operations	1.59		0.27			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	$12.27		$10.68			$10.41		$	9.64		$12.56		$14.42
Total Return(5)	14.89	%‡	2.59	%		7.99	%		(22.25	)%	(10.51	)%	26.49	%‡
Net Assets, End of Period (000s)	$18,247		$18,305			$21,482			$17,431		$26,932		$26,273
Ratios to Average Net Assets:
Expenses(6)	2.24	%†	2.17	%(7)		2.10	%		2.24	%	2.25	%(7)	2.27	%(7)†
Net investment loss	(0.96	)†	(1.12	)		(1.05	)		(1.33	)	(1.37	)	(1.42	)†
Portfolio Turnover Rate	15	%	65	%		68	%		26	%	34	%	26	%

(1	)	On April 29, 2004, Class L shares were renamed Class C shares.
(2	)	For the six months ended April 30, 2005 (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	)	Performance figures may reflect voluntary fee waivers and/or expense reimbursements. Past performance is no guarantee of future results. In the absence of voluntary fee waivers and/or expense reimbursements, the total return would have been lower.
(6	)	As a result of voluntary expense limitations, the ratio of expenses to average net assets will not exceed 2.25% for Class C shares.
(7	)	The investment manager voluntarily waived a portion of its fees and/or reimbursed expenses for the years ended October 31, 2004, 2001 and for the period ended October 31, 2000. If such fees were not voluntarily waived and/or expenses not reimbursed, the expense ratios would have been 2.21%, 2.28% and 2.68% (annualized), respectively.
‡		Total return is not annualized, as it may not be representative of the total return for the year.
†		Annualized.

See Notes to Financial Statements.

13 Smith Barney Sector Series Inc. | 2005 Semi-Annual Report

Notes to Financial Statements (unaudited)

1. Organization and Significant Accounting Policies

The Smith Barney Health Sciences Fund (“Fund”) is a separate non-diversified investment fund of the Smith Barney Sector Series (“Company”), a Maryland corporation, which is registered under the Investment Company Act of 1940, as amended, as an open-end management investment company.

The following are significant accounting policies consistently followed by the Fund and are in conformity with U.S. generally accepted accounting principles (“GAAP”). 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.

(a) Investment Valuation. Equity securities for which market quotations are available are valued at the last sale price or official closing price on the primary market or exchange on which they trade. Debt securities are valued at the mean between the bid and asked price provided by an independent pricing service that are based on transactions in debt obligations, quotations from bond dealers, market transactions in comparable securities and various relationships between securities.When prices are not readily available, or determined to reflect fair value, such as when the value of a security has been significantly affected by events after the close of the exchange or market on which the security is principally traded, but before the Fund calculates its net asset value, the Fund may value these investments at fair value as determined in accordance with the procedures approved by the Fund’s Board of Directors. Short-term obligations with maturities of 60 days or less are valued at amortized cost, which approximates market value.

(b) Repurchase Agreements. When entering into repurchase agreements, it is the Fund’s policy that its custodian or a third party custodian take possession of the underlying collateral securities, the market 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 market 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.

(c) Concentration 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.

(d) Security Transactions and Investment Income. Security transactions are accounted for on a trade date basis. Interest income, adjusted for amortization of premium and accretion of discount, is recorded on the accrual basis. Dividend income is recorded on the ex-dividend date. Foreign dividend income is 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. The cost of investments sold is determined by use of the specific identification method.

(e) Distributions to Shareholders. Distributions from net investment income and distributions of net realized gains, if any, are declared at least annually. Distributions to shareholders of the Fund are recorded on the ex-dividend date and are determined in accordance with income tax regulations, which may differ from GAAP.

14 Smith Barney Sector Series Inc. | 2005 Semi-Annual Report

Notes to Financial Statements (unaudited) (continued)

(f) Class Accounting. Investment income, common expenses and realized/unrealized gain (loss) on investments are allocated to the various classes of the Fund on the basis of daily net assets of each class. Fees relating to a specific class are charged directly to that class.

(g) Federal and Other Taxes. It is the Fund’s policy to comply with the federal income and excise tax requirements of the Internal Revenue Code of 1986, as amended, applicable to regulated investment companies.Accordingly, the Fund intends to distribute substantially all of its taxable income and net realized gains on investments, if any, to shareholders each year. Therefore, no federal income tax provision is required in the Fund’s financial statements. Under the applicable foreign tax laws, a withholding tax may be imposed on interest, dividends and capital gains at various rates.

(h) Reclassifications. GAAP requires that certain components of net assets be adjusted to reflect permanent differences between financial and tax reporting. These reclassifications have no effect on net assets or net asset values per share.

2. Management Agreement and Other Transactions with Affiliates

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.

During the six months ended April 30, 2005, the Fund’s Class A, B, and C shares had voluntary expense limitations in place of 1.50%, 2.25%, and 2.25%, respectively.These expense limitations can be terminated at any time by SBFM. During the six months ended April 30, 2005, SBFM voluntarily reimbursed the Fund for certain expenses in the amount of $8,471.

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, 2005, the Fund paid transfer agent fees of $31,922 to CTB.

In addition, for the six months ended April 30, 2005, the Fund also paid $4,001 to other Citigroup affiliates for shareholder recordkeeping services.

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

There is a maximum 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 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 a sales charge.

15 Smith Barney Sector Series Inc. | 2005 Semi-Annual Report

Notes to Financial Statements (unaudited) (continued)

For the six months ended April 30, 2005, CGM and its affiliates received sales charges of approximately $39,000 on sales of the Fund’s Class A shares. In addition, for the six months ended April 30, 2005, CDSCs paid to CGM and its affiliates were approximately $38,000 for Class B shares.

All officers and one Director of the Company are employees of Citigroup or its affiliates and do not receive compensation from the Company.

3. Investments

During the six months ended April 30, 2005, the aggregate cost of purchases and proceeds from sales of investments (excluding short-term investments) were as follows:

Purchases	$10,052,546
Sales	16,620,672

At April 30, 2005, the aggregate gross unrealized appreciation and depreciation of investments for federal income tax purposes were substantially as follows:

Gross unrealized appreciation	$11,429,335
Gross unrealized depreciation	(5,238,510	)
Net unrealized appreciation	$ 6,190,825

4. 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, 2005, 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	$25,373	$143,370	$90,675
For the six months ended April 30, 2005, total Transfer Agency Services expenses were as follows:
	Class A	Class B	Class C
Transfer Agency Services Expenses	$23,804	$28,265	$15,868
For the six months ended April 30, 2005, total Shareholder Communication expenses were as follows:
	Class A	Class B	Class C
Shareholder Communication Expenses	$9,421	$13,141	$7,439

16 Smith Barney Sector Series Inc. | 2005 Semi-Annual Report

Notes to Financial Statements (unaudited) (continued)

5. Capital Shares

At April 30, 2005, 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.

Transactions in shares of each class were as follows:
	Six Months Ended					Year Ended
	April 30, 2005					October 30, 2004
	Shares			Amount		Shares			Amount
Class A
Shares sold	203,377		$	2,441,517		364,847		$	4,170,489
Shares reacquired	(246,139	)		(2,942,654	)	(544,455	)		(6,221,756	)
Net Decrease	(42,762	)	$	(501,137	)	(179,608	)	$	(2,051,267	)
Class B
Shares sold	97,347		$	1,124,646		246,288		$	2,751,788
Shares reacquired	(363,514	)		(4,177,316	)	(596,977	)		(6,599,087	)
Net Decrease	(266,167	)	$	(3,052,670	)	(350,689	)	$	(3,847,299	)
Class C†
Shares sold	50,093		$	575,996		160,016		$	1,772,534
Shares reacquired	(275,623	)		(3,156,989	)	(509,931	)		(5,639,347	)
Net Decrease	(225,530	)	$	(2,580,993	)	(349,915	)	$	(3,866,813	)

†  On April 29, 2004, Class L shares were renamed as Class C shares.

6. Capital Loss Carryforward

On October 31, 2004, the Fund had a net capital loss carryforward of approximately $15,100,451, of which $478,325 expires in 2009, $5,690,484 expires in 2010 and $8,931,642 expires in 2011. These amounts will be available to offset any future taxable capital gains.

7. Additional Information

On May 31, 2005, the U.S. Securities and Exchange Commission (“SEC”) issued an order in connection with the settlement of an administrative proceeding against Smith Barney Fund Management LLC (“SBFM”) and Citigroup Global Markets Inc. (“CGMI”) relating to the appointment of an affiliated transfer agent for the Smith Barney family of mutual funds (the “Funds”).

The SEC order finds that SBFM and CGMI willfully violated Section 206(1) of the Investment Advisers Act of 1940 (“Advisers Act”). Specifically, the order finds that SBFM and CGMI knowingly or recklessly failed to disclose to the boards of the Funds in 1999 when proposing a new transfer agent arrangement with an affiliated transfer agent that: First Data Investors Services Group (“First Data”), the Funds’ then-existing transfer agent, had offered to continue as transfer agent and do the same work for substantially less money than before; and that Citigroup Asset Management (“CAM”), the Citigroup business unit that includes the fund’s investment manager and other investment advisory companies, had entered into a side letter with First Data under which CAM agreed to recommend the appointment of First Data as sub-transfer agent to the affiliated transfer agent in exchange, among other things, for a guarantee by First Data of specified amounts of asset management and investment banking fees to CAM and CGMI. The order also finds that SBFM and CGMI willfully violated Section 206(2) of the Advisers Act by virtue of the omissions discussed above and other misrepresentations and omissions in the materials provided to the Funds’ boards, including the failure to make clear that the affiliated transfer agent would earn a high profit for performing limited functions while First Data continued to perform almost all of the transfer agent functions, and the suggestion that the proposed

17 Smith Barney Sector Series Inc. | 2005 Semi-Annual Report

Notes to Financial Statements (unaudited) (continued)

arrangement was in the Funds’ best interests and that no viable alternatives existed. SBFM and CGMI do not admit or deny any wrongdoing or liability. The settlement does not establish wrongdoing or liability for purposes of any other proceeding.

The SEC censured SBFM and CGMI and ordered them to cease and desist from violations of Sections 206(1) and 206(2) of the Advisers Act. The order requires Citigroup to pay $208.1 million, including $109 million in disgorgement of profits, $19.1 million in interest, and a civil money penalty of $80 million. Approximately $24.4 million has already been paid to the Funds, primarily through fee waivers. The remaining $183.7 million, including the penalty, has been paid to the U.S. Treasury and will be distributed pursuant to a plan to be prepared by Citigroup and submitted within 90 days of the entry of the order for approval by the SEC. The order also requires that transfer agency fees received from the Funds since December 1, 2004 less certain expenses be placed in escrow and provides that a portion of such fees may be subsequently distributed in accordance with the terms of the order.

The order requires SBFM to recommend a new transfer agent contract to the Fund boards within 180 days of the entry of the order; if a Citigroup affiliate submits a proposal to serve as transfer agent or sub-transfer agent, an independent monitor must be engaged at the expense of SBFM and CGMI to oversee a competitive bidding process. Under the order, Citigroup also must comply with an amended version of a vendor policy that Citigroup instituted in August 2004. That policy, as amended, among other things, requires that when requested by a Fund board, CAM will retain at its own expense an independent consulting expert to advise and assist the board on the selection of certain service providers affiliated with Citigroup.

At this time, there is no certainty as to how the proceeds of the settlement will be distributed, to whom such distributions will be made, the methodology by which such distributions will be allocated, and when such distributions will be made. Although there can be no assurance, Citigroup does not believe that this matter will have a material adverse effect on the Funds.

8. Legal Matters

Beginning in June 2004, class action lawsuits alleging violations of the federal securities laws were 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, including the Fund (the “Funds”), and directors or trustees of the Funds (collectively, the “Defendants”). The complaints alleged, 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 alleged 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 also alleged that the Funds failed to adequately disclose certain of the allegedly wrongful conduct. The complaints sought 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.

On December 15, 2004, a consolidated amended complaint (the “Complaint”) was filed alleging substantially similar causes of action.While the lawsuit is in its earliest stages, to the extent that the Complaint purports to state causes of action against the Funds, Citigroup Asset Management believes the Funds have significant defenses to such allegations, which the Funds intend to vigorously assert in responding to the Complaint.

Additional lawsuits arising out of these circumstances and presenting similar allegations and requests for relief may be filed against the Defendants in the future.

18 Smith Barney Sector Series Inc. | 2005 Semi-Annual Report

Notes to Financial Statements (unaudited) (continued)

As of the date of this report, Citigroup Asset Management and the Funds believe that the resolution of the pending lawsuit will not have a material effect on the financial position or results of operations of the Funds or the ability of the Advisers and their affiliates to continue to render services to the Funds under their respective contracts.

9. Subsequent Event

On June 24, 2005, Citigroup announced that it has signed a definitive agreement under which Citigroup will sell substantially all of its worldwide asset management business to Legg Mason, Inc. (“Legg Mason”).

As part of this transaction, SBFM (the “Manager”), currently an indirect wholly owned subisidiary of Citigroup, would become an indirect wholly owned subsidiary of Legg Mason. The Manager is the investment adviser to the Fund.

The transaction is subject to certain regulatory approvals, as well as other customary conditions to closing. Subject to such approvals and the satisfaction of the other conditions, Citigroup expects the transaction to be completed later this year.

Under the Investment Company Act of 1940, consummation of the transaction will result in the automatic termination of the investment management contract between the Fund and the Manager.Therefore, the Fund’s Board of Directors will be asked to approve a new investment management contract between the Fund and the Manager. If approved by the Board, the new investment management contract will be presented to the shareholders of the Fund for their approval.

19 Smith Barney Sector Series Inc. | 2005 Semi-Annual Report

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SMITH BARNEY
H E A L T H  S C I E N C E S  F U N D

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

Smith Barney Sector Series Inc.

Smith Barney Health Sciences Fund		This report is submitted for the general information of the shareholders of Smith Barney Sector Series Inc. —
The Fund is a separate investment fund of the Smith Barney Sector Series Inc., a Maryland corporation.		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 report 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
		investing.
		www.citigroupam.com
	The Fund files its complete schedule of portfolio holdings with the Securities and Exchange Commission for the first and third quarters of each fiscal year on Form N-Q. The Fund’s Forms N-Q are available on the Commission’s website at www.sec.gov. The Fund’s Forms N-Q may be reviewed and copied at the Commission’s Public Reference Room in Washington D.C., and information on the operation of the Public Reference Room may be obtained by calling 1-800-SEC-0330. To obtain information on Form N-Q from the Fund, shareholders can call 1-800-451-2010.
	Information on how the Fund voted proxies relating to portfolio securities during the 12-month period ended June 30, 2004 and a description of the policies and procedures that the Fund uses to determine how to vote proxies relating to portfolio securities is available (1) without charge, upon request, by calling 1-800-451-2010, (2) on the Fund’s website at www.citigroupam.com and (3) on the SEC’s website at www.sec.gov.	©2005 Citigroup Global Markets Inc. Member NASD, SIPC  FD02553 6/05                                     05-8647

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.	SCHEDULE OF INVESTMENTS.
	Not applicable.
ITEM  7.	DISCLOSURE OF PROXY VOTING POLICIES AND PROCEDURES FOR CLOSED-END MANAGEMENT INVESTMENT COMPANIES.
	Not applicable.
ITEM  8.	[RESERVED]
ITEM  9.	PURCHASES OF EQUITY SECURITIES BY CLOSED-END MANAGEMENT INVESTMENT COMPANY AND AFFILIATED PURCHASERS.
	Not applicable.
ITEM  10.	SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS.
	Not applicable.
ITEM  11.	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 12.	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 8, 2005

     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 8, 2005

By:	/s/ Kaprel Ozsolak
	Kaprel Ozsolak
	Chief Financial Officer of
	Smith Barney Sector Series Inc.
Date: July 8, 2005