Purpose: This study was to determine the effects of laughter therapy on stress response and pain of military patients with low back pain. Method: The subjects in the experimental group received 3-sessions of laughter therapy on 3 consecutive days. The primary outcome measures were state anxiety, depression, blood pressure, pulse rate and pain. Result: After 3 sessions of laughter therapy, the scores of state anxiety(p=.046), depression(p=.028) and pulse rate(p=.003) were significantly lower and diastolic blood pressure(p=.038) was significantly higher in the experimental group than those in the control group. The level of pain(p=.711) was not different significantly between two groups. Conclusion: Laughter therapy could be an effective strategic intervention for military patients with low back pain to reduce the level of anxiety and depression. Further studies are needed to determine long-term effects of laughter therapy and its effects on cardiovascular system and pain.