The purpose of this study was to identify subjects with Post-traumatic Stress Disorder (PTSD) consequent to hallucinations and delusions and the experiences related to psychosis in schizophrenic and bipolar subjects. Schizophrenic and bipolar subjects were given questionnaires in order to evaluate PTSD incidence and symptoms. Subjects with classical types of trauma were excluded. Depression and stress scales were also answered. About one-third of schizophrenic subjects and one-half of bipolar subjects met PTSD criteria on the Penn PTSD Inventory. Hallucinations and delusions were identified as traumatic events in 60% of subjects with schizophrenia, but in only 15% of the subjects with bipolar disorder. Also, childhood abuse and various present stressors may contribute to the current PTSD symptomatology. Increases in PTSD scale scores were paralleled by increases in Beck depression scale scores. This study underscores the need for mental health clinicians to be sensitive to patients' illness experiences and to be aware of the therapeutic implications in treating PTSD in subjects with schizophrenia and bipolar illnesses.