In preventing transmission to uninfected drug users, the primary level of prevention is to prevent or stop drug users from using needles for ingesting drugs. Drug treatment to stop drug use entirely should be a major thrust. Some drug users will continue to use and share needles and syringes despite the availability of sterile equipment and educational attempts to reduce high-risk behavior. Attempts to advise such addicts on needle sterilization may be beneficial. For drug users who are already infected but clinically well, the aforementioned strategies are important for preventing the spread of the virus. Bearing children, particularly for seropositive women, should be discussed in detail. In areas of low AIDS prevalence among drug users, antibody test screening will help assess the degree to which HIV has entered the community, thus assisting in the development of public-health control measures. In areas of moderate to high AIDS prevalence among drug users, screening may serve the clinical purpose of reinforcing appropriate behaviors to reduce risk. 10 references.