Introduction. To assess sexual risk behavior for human immunodeficiency virus (HIV) infection and other sexually transmitted diseases (STD) in males with psychotic disorders and to compare it to that of the patients without these disorders. Methods. We used a structured interview to collect information regarding sexual risk behavior, knowledge about HIV/AIDS, history of STD and drug use. We included 106 patients with psychotic disorders from a psychiatric institution and 89 control medical out-patients from a general hospital. Results. Among psychotic patients, 70.8% declared that they had had sexual intercourse at some time in their lives and 37.7% during the last year. The psychotic patients had significantly less knowledge about HIV/AIDS than the controls and they had a smaller proportion of stable sexual partners and greater frequency of sexual risk behaviors, such as inconsistent condom use and sexual intercourse with prostitutes. In psychotic patients, inconsistent condom use was associated with more hospitalizations. Conclusions. Although patients with psychotic disorders have reduced sexual activity, they present greater frequency of sexual risk behaviors that predispose them to acquire HIV infection and other STD.