Costco Wholesale Corporation Reports March Sales Results and Plans for Membership Fee Increase.

ISSAQUAH, Wash. -- Costco Wholesale Corporation (Nasdaq: COST) today reported net sales of $5.36 billion for the five weeks ended April 2, 2006, an increase of 10 percent from $4.87 billion in the same five-week period of the prior fiscal year. For the first thirty-one weeks of its fiscal year ended April 2, 2006, the Company reported net sales of $33.91 billion, an increase of 11 percent from $30.49 billion during the similar thirty-one-week period of the prior fiscal year.

Comparable sales for the 5-week and 31-week periods ended April 2, 2006, were as follows:

5 Weeks                31 Weeks
                       ----------------------- -----------------------
US                               7%                      8%
International                    9%                      9%

Total Company                    7%                      8%
                       ======================= =======================

This year's five-week period included 35 days of sales compared to 34 days last year, reflecting the timing of Easter. This calendar shift impacted sales positively by approximately one to two percent.

Additional discussion of these sales results is available on a pre-recorded telephone message. You can access the recording by dialing 1-800-642-1687 (conference ID# 5367791). This recorded message will be available today through 5:00 p.m. (PT) on Friday, April 7, 2006.

In addition, the Company announced its plan to increase annual membership fees by $5 for its U.S. and Canada Gold Star (individual), Business, and Business Add-on Members, effective May 1, 2006. The Company's Executive Membership Program, which offers the U.S. and Canada members access to additional services, as well as participating in a 2% annual reward program of up to $500 per year, will continue to be offered at $100 per year. Approximately 15 million members will be impacted by the $5 annual fee increase, the first increase in nearly six years.

The Company plans to release its third quarter fiscal year 2006 operating results, for the twelve weeks ended May 7, 2006, on Wednesday, May 31, 2006. A conference call to discuss these third quarter results is scheduled for 8:00 a.m. (PT) on May 31 and will be available via a webcast on www.costco.com (click on Investor Relations and "Webcasts").

Costco currently operates 473 warehouses, including 346 in the United States and Puerto Rico, 68 in Canada, 17 in the United Kingdom, five in Korea, four in Taiwan, five in Japan and 28 in Mexico. 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 an additional 17 to 19 new warehouses, including the relocation of one warehouse to a larger and better-located facility, prior to the end of its 53-week 2006 fiscal year ending on September 3, 2006.

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, consumer and small business spending patterns and debt levels, conditions affecting the acquisition, development, ownership or use of real estate, actions of vendors, rising costs associated with employees (including health care and workers' compensation costs), rising costs associated with the acquisition of merchandise (including the direct and indirect effects of the rising cost of petroleum-based products and fuel and energy costs), 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.