A questionnaire investigation among 430 homosexual persons all of whom were members of an organization for homosexuals was completed by 144 (33%). These replies showed that they knew about HIV infection, risk behaviour and "safe sex". Their knowledge about the signs of HIV infection and AIDS was, however, more limited. The replies were compared with an age-matched group of the male population. The results of the investigation provide reasons to suppose that the information campaigns have been of value but information to prevent spread of infection is still necessary. In addition, further information is necessary about the subjective signs of HIV-infection so that persons in whom these signs develop may be offered the best possible treatment as early as possible.