It has been reported that cold-restraint stress significantly decreases hepatic and gastric glutathione and increases lipid peroxidation levels. In the present study, the effect of calcitonin on gastric and hepatic glutathione and lipid peroxidation levels after cold-restraint stress exposure was investigated in rats. Calcitonin pretreatment did not significantly influence the gastric glutathione and lipid peroxidation levels but significantly increased the hepatic glutathione and lipid peroxidation levels. Our results suggest that the anti-ulcerogenic effect of calcitonin is not related to changes in the gastric lipid peroxidation and glutathion levels. The effects of calcitonin on hepatic glutathione and lipid peroxidation must be further evaluated.