Blood glutathione-peroxidase (GSH-Px) was determined in 61 healthy subjects and 506 patients with various skin disorders. Depressed levels were observed in patients with psoriasis, eczema, atopic dermatitis, vasculitis, mycosis fungoides and dermatitis herpetiformis. Low values of GSH-Px were also found in some patients with pemphigoid, acne conglobata, polymyositis, rheumatoid arthritis, scleroderma and systemic lupus erythematodes. Vegetarian diet, malnutrition and alcohol abuse could possibly account for the low values in some patients. Fifty patients with low GSH-Px levels were treated with tablets containing 0.2 mg selenium as Na2SeO3 and 10 mg tocopheryl succinate. The GSH-Px levels increased slowly within 6-8 weeks of treatment. The clinical effect was encouraging and calls for controlled studies.