OBJECTIVE: The authors used data collected before military service to assess predictors of combat-related lifetime symptoms of posttraumatic stress disorder (PTSD). METHOD: The subjects were 131 male Vietnam and Vietnam-era veterans who had taken the MMPI in college and who were interviewed as adults with the Structured Clinical Interview for DSM- III-R. Scores on the basic MMPI scales were used to predict combat exposure, lifetime history of any PTSD symptoms given exposure, and lifetime PTSD classification (symptoms only, subthreshold PTSD, or full PTSD). RESULTS: Group means on the MMPI scales were within the normal range. No scale predicted combat exposure. Hypochondriasis, psychopathic deviate, masculinity-femininity, and paranoia scales predicted PTSD symptoms. Depression, hypomania, and social introversion predicted diagnostic classification among subjects with PTSD symptoms. The effects persisted when amount of combat exposure was controlled for. CONCLUSIONS: Pre-military personality can affect vulnerability to lifetime PTSD symptoms in men exposed to combat.Abstract Teaser