Using a standardized survey (325 participants) and guided in-depth (22 participants) interviews, data was collected regarding patterns of drug use and injection, needle sharing and cleaning, sexual behavior, beliefs about risk-reduction methods, and sources of health information. Most of the IVDUs used heroin, speedballs, and cocaine (in order of frequency) and shared needles (87.9 percent), while 40.3 percent sterilized their equipment. The prevalence of HIV seropositivity was 5.7 percent. The exchange of sex for money or drugs was reported in 60.7 percent of sexually active females and 20.5 percent of male IVDUs. Despite the concern regarding the risk for HIV infection, only 48.3 percent of IVDUs modified their injecting practices and 33 percent changed their risky sexual practices. Differences in drug use, sexual practices, and drug treatment history were related to gender, ethnicity, age, and type of drug injected. Implications of these findings are presented for the development of an AIDS risk-reduction program. 5 notes, 3 tables, and 25 references