For a study designed to examine the accuracy of information about HIV transmission, risk behavior, and preventive measures among individuals with psychiatric disorders in Italy, 214 psychiatric patients-114 outpatients and 100 inpatients-and 88 nonpsychiatric patients completed the AIDS Risk Behavior Knowledge Test. Levels of knowledge were lower among psychiatric patients than among control subjects. Patients with chronic illness and a diagnosis of schizophrenia were found to have less knowledge than other patients about HIV transmission. These findings confirm the need for HIV-related educational and behavior-modification programs for patients with chronic and severe mental illness in the community in Italy.