Fifty-four newly referred psychiatric outpatients were interviewed and a life history of severe traumatic experiences was taken. Forty-four gave a positive history, 17 of whom developed symptoms of post-traumatic stress (PTSS). Twelve met a past or current diagnosis of PTSD. Factors relating to the occurrence of PTSS included early trauma, more traumatic events, incest, perceiving the event as frightening, being physically injured, perceiving the event as being life threatening, seeing a physician, and being hospitalized. Age at trauma and differences between men and women are also discussed. © 1990 Plenum Publishing Corporation.