OBJECTIVE: The authors' goal was to assess the incidence of breast cancer among chronic psychiatric patients. METHOD: They reviewed mammograms and charts of 275 female patients over the age of 40 in a state psychiatric hospital and 928 women of comparable age at a general hospital radiology clinic. RESULTS: The incidence of breast cancer documented by pathology reports among the psychiatric patients was more than 3.5 times higher than that of patients at the general hospital and 9.5 times higher than the reported incidence in the general population. CONCLUSIONS: If confirmed, the suspected higher incidence of breast cancer among the psychiatric patients might be due to medications and further underscores the need for screening mammograms for breast cancer in these patients.