This study was designed to investigate the efficacy of the antidepressant fluvoxamine in the treatment of combat-related post-traumatic stress disorder (PTSD). Fifteen veterans with combat-related PTSD and no other psychiatric diagnosis except depression were recruited to participate in a 14-week open-label study of fluvoxamine. Patients underwent a 30-day washout period and were rated with the Clinician Administered PTSD Scale (CAPS), Mississippi Scale, Beck Depression Inventory (BDI), Hamilton Rating Scale for Depression (HAM-D) and Hamilton Rating Scale for Anxiety (HAM-A) at baseline, and every 2 weeks until week 14. Three patients stopped fluvoxamine prematurely due to side effects and 7 withdrew consent before completing the 14-week trial. Eight patients completed at least 8 weeks of treatment. The total daily dose of fluvoxamine ranged from 100 to 300 mg with a mean daily dose of 150 mg at week 14. Intent-to-treat analysis revealed a significant improvement in total CAPS scores, and in the intrusion and the avoidance/numbing subscales. The CAPS hyper-arousal scores did not change significantly. HAM-A score also improved significantly. No significant changes were seen on the Mississippi scale, HAM-D, or Beck Depression Inventory in the intent-to-treat analysis. In summary, our study shows that fluvoxamine appears to improve combat-related PTSD symptoms but not depressive symptoms. The high attrition rate and lack of a placebo group limits the conclusions of our study. Controlled studies of fluvoxamine in the treatment of PTSD are warranted.