The purpose of the present study was to investigate the effects of aerobic exercise on childhood PTSD, depression, and anxiety. Fifteen participants, ages 14 to 17, who met DSM-IV Criteria for PTSD were recruited from an all female residential treatment center Participants engaged in an aerobic exercise program for 40 minutes, three times per week, for a total of 8 weeks. Measures included were the Children's PTSD Inventory, the UCLA Post-Traumatic Stress Disorder Reaction Index for DSM-IV, Children's Depression Inventory, and the Revised Children's Manifest Anxiety Scale. Measures were administered twice at pre-intervention, again at mid-intervention, post-intervention, and at a one-month follow-up. This small n study utilized a staggered baseline, pre/post repeated measures design. Results of this study provided support for the positive effects of aerobic exercise on reducing PTSD, depression, and anxiety. Fewer participants met full criteria for PTSD after exercising. This research is a starting point toward satisfying the essential need to establish efficacious methods to treat PTSD and associated symptoms in child/adolescent populations.