The present study investigated self-reported and interpersonal hostility in 70 Vietnam combat veterans with and without posttraumatic stress disorder (PTSD) and 60 comparison community volunteer subjects. Veterans were 50 help-seeking, male Vietnam combat veterans with PTSD and 20 non-help-seeking male combat veterans without PTSD. Vietnam veterans with PTSD not only reported more hostility than non-PTSD veterans and healthy community volunteers, but also reacted behaviorally with more hostility during an interpersonal interaction. Compared to veterans without PTSD, veterans with PTSD reported significantly higher levels of hostility and demonstrated significantly greater non-verbal expressions of hostility during an interpersonal task. These results suggest that the level of hostility in PTSD combat veterans may be high as compared to comparison groups. The implications of these results and possible research directions are presented.