This study compares HIV/AIDS knowledge, attitudes, sexual behaviors, and behavioral intentions o f persons with serious mental illness (SMI), with those o f a community sample. Findings indicate that a sub group o f persons with SMI are sexually active and engage in HIV-risk behaviors. Despite higher levels o f cognitive impairment among persons with SMI, no differences were found in level o f knowledge about HIV/AIDS; both groups are relatively well informed about transmission routes, populations at risk, and medical facts. However, persons with SMI are more concerned about the possibility o f HIV infection and perceive themselves as comparatively helpless in the face o f the threat.AIDS has not been perceived as a threat to persons with serious mental illness (SMI) because of the prevailing stereotype that they are asexual or not interested in sex. In rare instances when persons with SMI are sexually active, the contact is assumed to be heterosexual (Harvey &c Trivelli, 1990). These assertions are now being rebutted. Recent research has documented that interpersonal sexual behavior is frequent among persons with SMI liv ing in the community (Lukoff, Gioia-Hasick, Sullivan, Golden, & Nuechterlein, 1986;Test, Burke, & Wallisch, 1990) as well as in inpatient settings (Wasow, 1980). Persons with SMI also report frequent homosexual behaviors (Rozensky &c Berman, 1984).Not only are persons with SMI more sexually active than once believed, they appear to be engaging in sexual behaviors that put them at high risk for HIV infection. In a recent study of 205 patients in an acute care inpatient unit, approximately 20% of the sample had engaged in HIV-risk behaviors, including homosexual contact and heterosexual contact with persons con sidered to be at high risk, such as intravenous drug users (IDUs) and/or pros titutes (Sacks, Silberstein, Weiler, 8c Perry, 1990). Among persons at risk but This document is copyrighted by the American Psychological Association or one of its allied publishers.This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.