This study estimated the rate and correlates of recent unprotected sex among sexually active psychiatric patients in Brazil, stratified by gender. The prevalence of unprotected sex among women and men were 89% and 77%, respectively. Significant correlates with unprotected sex were: being married/in union, living with children/partner, and cigarette smoking in both genders; lower income, depression and anxiety diagnoses among men only; older age, no previous HIV testing, sex under the influence of alcohol/drugs, and verbal violence among women only. Interventions to reduce risk behavior among psychiatric patients in Brazil are urgent and should take into account gender differences.