PURPOSE: The purpose of this study was to investigate the role of mast cells and their product, histamine and leukotriene in ischemia-reperfusion injury. METHODS: Forty Sprague-Dawley rats were divided into four groups. (Group I: Control group without ischemia, Group II: Normal saline with ischemia, Group III: Cimetidine with ischemia, Group IV: Zafirlukast with ischemia) Skin flap was elevated and ischemic insult was given by clamping the artery for 12 hours. Before reperfusion, the rats were treated with saline, cimetidine and zafirlukast. Flap survival was evaluated at 7 days. Neutrophil counts, mast cell counts were evaluated 24 hours after reperfusion. RESULTS: Flap survival rate in the control group was 92.33%, whereas normal saline group had 37.34% survivals. Cimetidine and zafirlukast treated group showed significantly higher survival rates than normal saline group. The neutrophil and mast cell counts in cimetidine and zafirlukast treated group were significantly decreased than normal saline group. Cimetidine treated group showed higher survival rate and lower cell counts than zafirlukast treated group. CONCLUSION: The administration of cimetidine and zafirlukast can decrease neutrophils and mast cells caused by ischemia-reperfusion and increase flap survivals. It is suggests that antihistamine and leukotriene receptor antagonist have protective effect against ischemia-reperfusion injury to skin flap in rat.