Stress-susceptible pigs were offered selenium-adequate diets containing either 20 IU vitamin E kg−1 or 260 IU vitamin E kg−1 and 500 mg vitamin C kg−1. Performance characteristics and carcase quality were not different between the two groups. During the feeding trial the pigs were exposed to halothane and “myostress”. Plasma pyruvate kinase, creatine kinase and thiobarbituric-acid reactive substances were used as indicators of damage to cell membranes. Subsequent to halothane intubation and to “myostress” injection antioxidant supplementation had a highly significant protective effect on cell membrane integrity. These results are compatible with previous suggestions that the porcine stress syndrome reflects an antioxidant abnormality which may be ameliorated by increasing the antioxidant content of the ration.