From May 1985 to December 1992, a total of 5,931,032 serum samples from eight population groups were tested for antibody to human immunodeficiency virus type 1 (HIV). Mandatory testing is carried out for blood donors, military recruits, immigrants, and prisoners. The other population groups were tested anonymously with consent. A total of 407 samples were seropositive. Of those HIV carriers, 63 developed AIDS: 37 were homosexuals, 6 were hemophiliacs, 1 was an intravenous drug user, 15 were heterosexuals, and 4 had no known risk factors. Although the prevalence of HIV infection and AIDS in Taiwan has remained low, the increase since 1988 has been rapid. Before 1987, all of the 48 persons with HIV infection were homosexuals or hemophiliacs. Thereafter, the risk groups diversified, with the main group shifting from homosexuals to heterosexuals and the number of intravenous drug users surpassing the number of hemophiliacs. Among the 63 patients with AIDS, 59 were male and only 4 were female; 53 have died (3 committed suicide).