WASHINGTON - The nation's first semipostal stamp dedicated to raising funds for research has been so popular, an additional 85 million stamps will be printed, the U.S. Postal Service announced today.

Last month, President Clinton signed legislation extending sales of the Breast Cancer Research "semipostal" stamp for another two years. To date the stamp, which costs 40 cents and is good for First-Class postage, has raised $15.7 million for research.

"Customers and postal employees shouldn't worry, however," said James C. Tolbert, Executive Director, Stamp Services. "The reprint of 85 million stamps will be sufficient for post offices throughout the country. We are working hard to make sure post offices are well supplied and customers' needs are met."

The Postal Service will begin shipping the latest printing of stamps to Stamp Distribution Offices by early September this year. This 85 million print run will bring the total of Breast Cancer Research stamps printed to 415 million, with about 223 million sold to date. The 85 million stamps will be sufficient to handle increased customer demand during Breast Cancer Awareness Month (October) and during the holiday season.

In 1997, legislation directed the Postal Service to issue a semipostal stamp that would be valid for postage but would cost an additional amount above the First-Class rate. After recovering reasonable costs, net proceeds from sales of the stamps are earmarked for research organizations. Seventy percent is given to the National Institutes of Health, and 30 percent is given to the Department of Defense. Both organizations were named in the legislation to receive the funds and are leaders in breast cancer research.