Twenty-four uremic patients on hemodialysis who had never been treated with vitamin E or related drugs and 12 control patients with normal renal function were studied. Hemodialysis patients were randomly divided into two groups; 12 were treated with oral vitamin E (300 mg/day) for eight weeks and 12 uremic patients and 12 controls were given placebo. Serum vitamin E, prolactin, FSH, LH, and free testosterone levels were measured in all patients before and after treatment. After the vitamin E treatment serum prolactin levels were significantly decreased (50.8 vs 15.4 ng/ml, p < 0.01). Vitamin E levels were significantly increased (1.11 vs 1.22 mg/dl, p < 0.05). Serum FSH, LH and free testosterone were not affected. In the other two groups there were no significant changes. These results show that vitamin E treatment lowers prolactin levels in uremic hemodialysis patients. This might be due to inhibition of central prolactin secretion. Vitamin E inhibits pituitary gland hypertrophy in vitamin E-deficient rats.