Thirty-two cows (Black-and-White x HF) in the first 100 days of lactation were divided into 4 groups and fed rations composed of equal proportions of roughages and concentrates in amount of 1 kg per 2 kg of milk at yield exceeding 12 kg/day. The concentrates were supplemented with vitamin E (group I , 336 mg; groups II , III, and IV, 672 mg/cow/day) and selenium: group I , no supplementation; group II , 4 mg/cow/day as sodium selenite; group III, 4 mg/cow/day as selenium yeast; group IV, 2 mg/cow/day as selenium yeast. Cows fed selenium-supplemented rations had significantly elevated serum selenium concentrations (group I, 0.0214 mcg/ml; II - 0.0453 mcg/ml; III, 0.0654 mcg/ml; IV, 0.0573 mcg/ml). Selenium from yeast was utilized better than sodium selenite. Regardless of the source of selenium, Se lowered serum a-tocopherol (0.245 vs 0.229; 0.187; 0,232 mg/dl) and retinol (35.57 vs 31.46; 32.25; 29.29 mcg/dl) levels. The addition of selenium when the vitamin E content of the ration was increased modified the lipid metabolism of cows (elevated HDL and triglycerides).