To determine if behavioral changes in intravenous drug users in Amsterdam have retarded the HIV (human immunodeficiency virus) epidemic in this group in recent years, we report that: HIV-antibody seroprevalence in annual samples of injectors has been constant over the years 1986-89; HIV-antibody incidence in a cohort of injectors appears to have decreased from 1986 to 1987 and stabilized after that until 1989; acute hepatitis B incidence in all drug users in Amsterdam declined rapidly between 1985-89. It is concluded that changes in drug use behavior so far appear to have resulted in a stabilization of the epidemic among injectors, at a level with a still disturbingly high incidence rate of 5-6 per 100 person-years.