This study reports for the first time on secular trends in human immunodeficiency virus (HIV) infection and AIDS, and possible associations with prevention policy in Austria. We analysed HIV seroprevalence and AIDS cases among intravenous drug users (IDU) and men who have sex with men (MSM). In this study we found a diminished rate of increase in new cases of AIDS and a decline in HIV seroprevalence among IDU but not among MSM. Among clients visiting HIV counselling and testing centres in Austria between 1987 and 1990, seroprevalence among IDU was estimated at 27.9% as compared to 19.6% between 1990 and 1992 (odds ratio (OR): 0.62; 0.45-0.85). Among MSM corresponding prevalence for these two periods was 12.1% and 10.9%, respectively, which was not a significant decline. In the period 1990 to 1994, the increase in AIDS cases per half-year levelled off for IDU (incidence rate ratio (IRR) :1.00; 0.99-1.01) but to a lesser extent among MSM (IRR: 1.01; 1.01-1.02). The most effective prevention policy intervention was considered to be the national Methadone Maintenance Program (MMTP), started in 1987, and the provision of sterile injection equipment. We observed that in the recent period there was a decline in the frequency of attendance among young (less than 28 years of age) MSM at counselling centres (OR: 1.27; 95 % CI: 1.08-1.49), accompanied by the observation that the rate of seroprevalence among this group did not decline. This is in contrast to young IDU where attendance did not decline but seroprevalence did. Although inference is limited from cross sectional studies, we argue for a reoriented and effectively monitored HIV prevention policy focused on young MSM.