PIP: The Centers for Disease Control (CDC) received reports of 593 cases of acquired immunodeficiency syndrome (AIDS) in the US between June 1, 1981, and September 15, 1982. Death occurred in 243 (41%) of these cases. The incidence of AIDS by date of diagnosis has roughly doubled every 6 months since late-1979, and an average of 1-2 cases are now diagnosed per day. The mortality rate for cases diagnosed over 1 year ago exceeds 60%. About 80% of AIDS cases are concentrated in 6 metropolitan areas, primarily on the east and west coasts. 75% of AIDS cases have involved homosexual or bisexual men, among whom the reported prevalence of intravenous drug abuse was 12%. Among the 20% of heterosexual cases, the prevalence of intravenous drug abuse was 60%. Reported AIDS cases can be separated into groups based on the following risk factors: homosexual or bisexual males--75%, intravenous drug abusers with no history of homosexual activity--13%, Haitians with neither a history of homosexuality or intravenous drug abuse--6%, persons with hemophilia A with no other risk factors--0.3%, and persons in none of the other groups--5%. 51% of AIDS victims had Pneumocystis carinii pneumonia (PCP) without Kaposi's sarcoma (KS), 30% had KS without PCP, 7% had both PCP and KS, and 12% had opportunistic infection alone. The overall mortality rate for cases of PCP without KS (47%) was more than twice that for cases of KS without PCP (21%), while the rate for cases of both PCP and KS (68%) was more than 3 times as great. The mortality rate for opportunistic infection with neither PCP or KS was 48%.