Post-traumatic stress disorder (PTSD) was studied in the Piedmont region of North Carolina. Among 2985 subjects, the lifetime and six month prevalence figures for PTSD were 1·30 and 0·44 % respectively. In comparison to non-PTSD subjects, those with PTSD had significantly greater job instability, family history of psychiatric illness, parental poverty, child abuse, and separation or divorce of parents prior to age 10. PTSD was associated with greater psychiatric co-morbidity and attempted suicide, increased frequency of bronchial asthma, hypertension, peptic ulcer and with impaired social support. Differences were noted between chronic and acute PTSD on a number of measures, with chronic PTSD being accompanied by more frequent social phobia, reduced social support and greater avoidance symptoms.