The research team of the Institute for Epidemiological Research on Drug Dependents interviewed a street sample of 157 persons and a sample of 123 persons undergoing inpatient treatment for drug addiction. Results showed that the emergence of AIDS had brought about a radical change in the environment of intravenous drug users, of whom about 40 percent were infected with HIV. Liberalized syringe sales had an obvious effect on the behavior of intravenous drug users in that about half of them did not share syringes and purchased them at pharmacies. The rest continued sharing syringes in a variety of ways. Results indicated that the decision to make syringes freely available for sale was not sufficient to cope with the problem of sharing syringes. Thus, additional educational programs are needed that are personalized and geared to each subject's special circumstances. 20 references. (Author abstract modified)