This study was carried out to evaluate whether antioxidant nutrient suppplementation with $alpha$-tocopherol, vitamin C, $eta$-carotene, and selenium reduces the lipid peroxide levels and increases the antioxidative enzyme activities in patients with coronary hart disease. Eighty nine patients participated in a randomized, double-blind, placebo-controlled trial. The antioxidant group (45 patients) was given daily doses of $alpha$-tocopherol (400 IU), vitamin C (50 mg), $eta$-carotene (15 mg), and selenium (50 $mu extrm{g}$) and forty four patients received a placebo. Thirty eight subjects (84.4%) of the antioxidant group and thirty nine subjects (88.6%) of the placebo group completed the three-month supplementation. Serum levels of tocopherol, vitamin C and $eta$-carotene significantly increased in the antioxidant group compared with the baseline (p<0.05). Thiobarbituric acid-reactive substances(TBARS) decreased significantly (0.6 nmol MDA/mL) in the antioxidant group compared with that (0.09 nmol MDA/mL) in the placebo group (p=0.03). However, antioxidant supplementation did not affect the level of oxidized-LDL measured as autoantibodies against oxidized-LDL. The superoxide dimutase activity in red blood cells increased in the antioxidant group compared with the baseline (p<0.05). However, glutathione peroxidase activities did not change after supplementation in both groups, and catalase activity significantly decreased in the placebo group (p<0.05). These results suggest that antioxidant supplementation for 3 months with $alpha$-tocopherol, vitamin C, $eta$-carotene and selenium in patients with coronary heat disease may be partially protective against oxidative stress.