PURPOSE: Evaluate the effectiveness of a 2-day, 3-night outdoor recreation intervention involving fly-fishing in reducing the psychological concomitants of stress among 74 veterans (M = 47.27, SD = 14.55 years) with post-traumatic stress disorder (PTSD). METHODS: Participants completed repeated assessments of attentiveness, mood, depression, anxiety, and somatic stress across 3 time periods, corresponding to 2 weeks before the trip (baseline), the last day of the trip, and a 6-week follow-up. Assessments of perceptual stress, PTSD symptoms, and sleep quality were also administered during the baseline and follow-up periods. RESULTS: Acute effects were observed for improvements in attentiveness and positive mood states, coupled with significant and sustained reductions in negative mood states, anxiety, depression, and somatic symptoms of stress. Comparisons between the baseline and follow-up periods revealed significant improvements in sleep quality and reductions in perceptual stress and PTSD symptoms. CONCLUSIONS: The current findings suggest that combat veterans with PTSD may benefit from participation in group-based outdoor recreation as a means to improve psychosocial well-being.