Two experiments were conducted to study effects of feeding young pigs diets low in vitamin E and selenium supplemented with d-α-tocopherol or selenium alone, or both. An analysis of the performance data showed that the supplementation of selenium or tocopherol, or both, to the semipurified diets had no significant effect on growth rate. Fifty-four percent of the pigs fed diets deficient in both vitamin E and selenium died before 14 weeks of age. Necropsy of these pigs showed hepatic necrosis, icterus, generalized edema, anemia, pale areas in skeletal and cardiac musculature, and a yellowish-brown discoloration of body fat. Prominent histologic lesions occurred in the liver and skeletal muscle tissues of pigs fed no supplemental selenium or tocopherol. Supplementing the diet with trace amounts of selenium, tocopherol or both reduced the mortality to 7 percent. Necropsy and histologic examination of the tissues from the pigs fed supplemented diets showed that no organ or tissue changes had occurred.