As of 1985, New York had 1,869 AIDS cases among drug users, New Jersey 490, and other States 781. Of these, 51 percent were black, 30 percent were Hispanic, and 80 percent were male. Research suggests that rapid dissemination of AIDS among drug users results from sharing needles among users and across friendship networks. Users are the primary source of heterosexual transmission in the United States. Recent research indicates that development of AIDS in seropositive individuals is higher than originally believed, and that the great majority of exposed users will have lifelong infection and detectable immune system impairment. Prevention of AIDS will require prevention of drug abuse and/or needle sharing, education, safer sexual practices, and screening of pregnant women at risk. 1 table and 42 references.