Effects of epidural anesthesia (EA) on free-radical lipid oxidation and the antioxidant system were studied in coronary patients during aortocoronary bypass operations and in the immediate postoperative period in comparison with patients operated on under common anesthesia (without EA). Thirty-six patients (men) aged 42.4 +/- 1.4 years were examined. EA as a component of total anesthesia in aortocoronary bypass surgery was conducive to a lesser activation of free-radical lipid oxidation. After surgery EA sooner normalized free-radical oxidation and the antioxidant system, which was observed at the end of the operation and during the first 24 h after it. During artificial circulation EA did not appreciably affect the degree of activation of free-radical oxidation.