Indications that psychosocial factors have an influence on the immune system lead to the study of the effects of psychosocial factors on the course of infection with Human Immunodeficiency Virus (HIV). In this article, results are described of studies of the associations between psychiatric problems and psychosocial factors such as negative life events, ways of coping, and social support on the one hand and progression of HIV infection in homosexual men on the other hand. In one prospective correlational study we found a positive association between the coping style `active confrontation with HIV infection' and progression of HIV infection, whereas in another similar study we found a positive association between the course of infection and the coping style `distraction of problems in general'. In a psychosocial intervention study we found that those subjects who reported less distress after the intervention showed a smaller decline in CD4 cell counts. Problems in interpreting these results are discussed, as well as results from other studies in this area. It can be concluded that the results are contradictory and that it is too early to draw definite conclusions.