HIV infection can be associated with major psychological and social disturbance. Psychosexual problems would be expected to arise in the context of the infection, in view of the contribution that sexual behaviour can make to the acquisition and spread of HIV infection. Here the results of a study of the psychosexual consequences of HIV infection in gay men and men with haemophilia are presented, with the inclusion of data from control groups. Sixteen HIV-positive and 23 HIV-negative gay men, and 20 HIV-positive and 24 HIV-negative men with haemophilia with sexual partners were studied. HIV infection was found to be associated with the greater risk of development of sexual dysfunction in seropositives, in particular in relation to ejaculatory difficulties, both delayed ejaculation in the case of gay men and men with haemophilia, and premature ejaculation in the case of men with haemophilia. Possible aetiological mechanisms are considered, including the possibility of organic disease. The findings are of relevance to those involved in the care of people with HIV infection.