OBJECTIVE: This study sought to determine the frequency and types of sexual behavior among patients with schizophrenia and to assess the behavior with respect to risk of HIV infection. METHOD: Ninety-five inpatients and outpatients with a research diagnosis of schizophrenia underwent a series of face-to-face interviews to determine their sexual activity and correlate it with demographic characteristics, psychopathology, and medication side effects. RESULTS: Forty-four percent of the patients had been sexually active in the preceding 6 months, and 62% of these had had multiple partners. Sexual activity was associated with greater general psychopathology. Having multiple sexual partners was associated with younger age, a lower level of functioning, the presence of delusions, and more positive symptoms. Of the sexually active patients, 12% reported at least one partner who was HIV positive or injected drugs, or both, and 50% had exchanged sex for money or goods. Ten percent of the patients had engaged in homosexual activity in the preceding 6 months and 22% during their lifetime; the frequency was similar among men and women. Consistent condom use was uncommon. CONCLUSIONS: A substantial proportion of schizophrenic patients had recent histories of sexual abstinence, but an almost equal number were sexually active. Sexual activity was usually accompanied by behavior related to HIV risk. Sexual activity and having multiple partners were associated with certain measures of more severe illness. Younger patients were more likely to have multiple partners but were also more likely to use condoms. There is a need for aggressive prevention strategies with this population.