A 10-week open-label trial of fluvoxamine was conducted for male Vietnam combat veterans with chronic PTSD. Subjects were excluded if they met full current criteria for panic disorder or agoraphobia, and lifetime criteria for psychosis, bipolar disorder, or organic mental syndrome. Repeated MANOVA was performed to determine change over time. Fluvoxamine was well tolerated; side effects were observed primarily early in treatment with headache, insomnia, sedation, and gastrointestinal distress being most frequent. Fluvoxamine was effective for treating the core intrusion, avoidance, and arousal symptoms of PTSD. Large treatment effects were seen by 4-6 weeks, and maintained at 10 weeks. The magnitude of change was greater than has been previously reported for antidepressant treatment of male Vietnam combat veterans with PTSD.