Since 1985, a number of Institutes of Forensic Medicine in Germany have cooperated in a multicenter study, to provide a constant monitoring of HIV-1-prevalence among drug related deaths. In 1990/91, the Institutes in Copenhagen, Stockholm, Vienna and Zürich also participated in this study. HIV-1-prevalence is decreasing in the German cities, whereas the epidemiological development is not uniform in the other major cities. Regional differences are obvious. In 1991, the prevalence rates were as follows: Berlin 15% (n = 220), Hamburg 4% (n = 179), Frankfurt 17% (n = 167), Munich 9% (n = 136), Stockholm 10% (n = 79), Copenhagen 14% (n = 130), Vienna 20% (n = 56), and Zürich 23% (n = 84).