A minority of people who test HIV seropositive continue to engage in sexual behaviour that places their partners at high risk for HIV infection. However, little is known about factors that contribute to sexual risk behaviour among HIV-seropositive men. In this study, HIV-seropositive men participating in substance abuse support groups and HIV prevention programmes (n=223) completed measures of demographic characteristics, sexual behaviour history, sensation-seeking (the propensity to seek optimal stimulation), and sexual compulsivity (persistent sexual preoccupations). Twenty-six per cent of the sample reported having recent multiple unprotected sexual intercourse partners. Across support group and prevention programme participants, men with multiple unprotected partners reported greater sexual compulsivity than men with one or no unprotected partners, but groups did not differ in terms of sensation-seeking. Results suggest that intensive therapeutic interventions are needed for a relatively small number of people who may contribute significantly to the HIV epidemic.