OBJECTIVE The purpose of this study was to determine whether intelligence predicts variance in posttraumatic stress disorder (PTSD) symptoms beyond that predicted by extent of combat exposure. METHODS The subjects were 105 male Vietnam combat veterans. They completed the Mississippi Scale for Combat-Related Posttraumatic Stress Disorder, the Combat Exposure Scale, and the Shipley Institute for Living Scale, a measure of general intelligence. Number of years of education was recorded for each subject. RESULTS Multiple regression analyses revealed that estimated full-scale IQ significantly predicted variance in PTSD symptoms beyond that predicted by extent of combat exposure. The lower a subject's intelligence, the more severe were his PTSD symptoms. CONCLUSIONS Cognitive variables may affect the ability to cope with trauma, thereby affecting whether a person develops chronic PTSD.