After the first screenings in 1985 had shown high HIV-seroprevalence rates, several preventive measures were initiated. Comprehensive information on AIDS and HIV transmission was provided during imprisonment, and efforts were made to improve cooperation between the prison outpatient psychiatric clinic, social workers, and other private and public drug treatment facilities. Drug abusers were either brought into contact with social workers linked to the various programs while serving their prison sentences or else were advised to contact support facilities after discharge. During the study, HIV-seroprevalence rates in drug-dependent inmates decreased 30 percent. A concomitant increase in admission to any kind of therapy programs and an increasing change from taking heroin intravenously to taking drugs orally was noted. Implications are drawn from the study. 4 figures and 45 references