We investigated the effects of TJ-35 (Shigyaku-san) on gastric mucosal injury induced by ischemia-reperfusion in rats; and using the electron spin resonance (ESR) spin trapping method, we also assessed its oxygen-derived free radical-scavenging activities. The increase in mucosal lesions and in thiobarbituric acid-reactive substances (as an index of lipid peroxidation) was significantly inhibited by the oral administration of 500 mg/kg of TJ-35; and in addition, TJ-35 demonstrated superoxide and hydroxyl radical-scavenging activities in vitro. These results suggest the possibility that the effects of TJ-35 on gastric mucosal injury induced by ischemia-reperfusion may be the result of its free radical-scavenging activities. © 1991, SOCIETY FOR FREE RADICAL RESEARCH JAPAN. All rights reserved.