Active participation in combat trauma increased reports of posttraumatic stress disorder (PTSD) symptoms over passive witnessing of trauma. Using archival data from 376 U.S. soldiers who took part in the family interview component of the 1988 National Vietnam Veteran Readjustment Study (NVVRS), findings are that even after statistically accounting for witnessing combat trauma, U.S. soldiers who likely killed enemy soldiers in combat reported elevated levels of PTSD symptoms. Both inference and direct self-reports were used to measure killing in combat, and both measures accounted equally well for variance in PTSD symptoms. The likelihood of a soldier killing enemy combatants was also weakly related to his spouse's report of physical domestic violence in the past year. Diagnosing the mental health symptoms of combat soldiers should specifically assess whether they actively participated in wounding or killing the enemy.