The medical histories of 200 schizophrenic patients were compared to those of 203 depressed patients, 122 manic patients, and 134 surgical controls. All subjects were hospital inpatients. Charts were specifically examined to record any head injury before age 10 that had required medical attention or caused loss of consciousness. Schizophrenics had a significantly greater history of head trauma than the manics, depressives, and surgical controls. There were no significant differences between manics and depressives or between affective disorders as a group and surgical controls. Childhood trauma may be a contributing factor to the development of psychosis in some individuals.