Exhibit 99.1

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COSTCO WHOLESALE CORPORATION REPORTS SECOND QUARTER AND YEAR-TO-DATE OPERATING RESULTS FOR FISCAL YEAR 2012, AND FEBRUARY SALES RESULTS

ISSAQUAH, Wash., February 29, 2012 – Costco Wholesale Corporation (“Costco” or the “Company”) (Nasdaq: COST) announced today its operating results for the second quarter (twelve weeks) and first half (24 weeks) of fiscal 2012, ended February 12, 2012, and its sales results for the four weeks ended February 26, 2012.

Net sales for the quarter increased ten percent, to $22.51 billion, from $20.45 billion last year. Net sales for the first half increased eleven percent, to $43.69 billion, from $39.27 billion last year.

Comparable sales were as follows:

Inflation in gasoline prices had a positive impact on comparable sales, particularly for the twenty-four-week period; foreign currencies had a negative impact, particularly for the twelve-week period. Excluding these effects, comparable sales were as follows:

Net income for the quarter was $394 million, or $.90 per diluted share, compared to $348 million, or $.79 per diluted share, last year. Net income for the first half was $714 million, or $1.62 per diluted share, compared to $660 million, or $1.49 per diluted share, last year.

The Company today also reported net sales of $7.04 billion for the four weeks ended February 26, 2012, an increase of ten percent from $6.38 billion in the same four-week period of the prior fiscal year. For the six-month retail reporting period of September through February, the twenty-six weeks ended February 26, 2012, which includes the first two weeks of the Company’s fiscal third quarter, the Company reported net sales of $47.22 billion, an increase of eleven percent from $42.46 billion during the comparable period of the prior fiscal year.

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Comparable sales for the 4-week retail-reporting month of February and the 26-week retail-reporting period of September through February were as follows:

Inflation in gasoline prices had a positive impact on comparable sales, particularly for the twenty-six week period; foreign currencies had a negative impact for both periods. Excluding these effects, comparable sales were as follows:

Costco currently operates 600 warehouses, including 433 in the United States and Puerto Rico, 82 in Canada, 32 in Mexico, 22 in the United Kingdom, 13 in Japan, eight in Taiwan, seven in Korea and three in Australia. The Company also operates Costco Online, an electronic commerce web site, at www.costco.com and at www.costco.ca in Canada. The Company plans to open up to an additional ten new warehouses (including the relocation of a warehouse to a larger and better-located facility) prior to the end of its fifty-three-week fiscal year on September 2, 2012.

A conference call to discuss these second quarter operating results and February sales is scheduled for 8:00 a.m. (PT) today, February 29, 2012, and is available via a webcast on www.costco.com (click on Investor Relations and “Play Webcast”).

Certain statements contained in this document constitute forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. For these purposes, forward-looking statements are statements that address activities, events, conditions or developments that the Company expects or anticipates may occur in the future. Such forward-looking statements involve risks and uncertainties that may cause actual events, results or performance to differ materially from those indicated by such statements. These risks and uncertainties include, but are not limited to, domestic and international economic conditions, including exchange rates, the effects of competition and regulation, uncertainties in the financial markets, and consumer and small business spending patterns and debt levels, conditions affecting the acquisition, development, ownership or use of real estate, actions of suppliers, rising costs associated with employees (including health care costs), energy and certain commodities, geopolitical conditions, and other risks identified from time to time in the Company’s public statements and reports filed with the Securities and Exchange Commission.

CONTACTS: Costco Wholesale Corporation

Richard Galanti, 425/313-8203, Bob Nelson, 425/313-8255, Jeff Elliott, 425/313-8264

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COSTCO WHOLESALE CORPORATION

CONDENSED CONSOLIDATED STATEMENTS OF INCOME

(dollars in millions, except per share data)

(unaudited)

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COSTCO WHOLESALE CORPORATION

CONDENSED CONSOLIDATED BALANCE SHEETS

(dollars in millions)

(unaudited)

Subject to Reclassifications