The Mammography Quality Standards Act (MQSA) became effective October 1, 1994, and requires all mammography facilities to meet quality standards as promulgated by the Food and Drug Administration (FDA). The FDA undertook an assessment of the MQSA federal certification requirements on the availability of mammography facilities.A survey of states on mammography facility closures between October 1, 1993, and October 1, 1994, was conducted. MapInfo software was used to link zip codes to demographic databases. The characteristics of closed facilities were compared to certified facilities as of December 15, 1994.A total of 369 facilities (3.5%) had closed. This closure rate was comparable to previous years' rates (2.5-10%). As of December 15, 1994, 10,142 certified facilities were operating. Relative to their distribution in the United States, closures in rural areas were proportional, but there were more facility closures in the minority areas and in poverty areas. However, the relative distributions of facilities to these areas' populations were unchanged.Impact on facility availability has been minimal.