Glutathione peroxidase activity and selenium and vitamin E levels were measured in the plasma and erythrocytes of 25 chronic alcoholic patients without liver cirrhosis before and after 14 days of abstinence from alcohol, and compared with the levels in 25 sex- and age-matched healthy controls. Before abstinence, all three levels were shown significantly depressed in the alcoholic patients compared with the controls, in both plasma (80, 71, and 89% of control values) and erythrocytes (68, 70, and 83% of control values). After a 14-day abstinence period with no dietary supplementation, a trend towards normalization was noted in erythrocyte (vitamin E and glutathione peroxidase 74 and 91% of control values respectively), in whole blood selenium (82%) and plasma in vitamin E (74%). However, plasma selenium and glutathione peroxidase values were lower than pre-abstinence values (76% and 86% of control values respectively). Our results point to a deficiency in the antioxidant defense system of chronic alcoholics before the occurrence of severe liver disease. This lack of protection against lipoperoxides is all the more important in circumstances like chronic alcohol consumption, in which lipid peroxidation is known to increase. However, the present study also demonstrated that during 14 days of a normal diet free of ethanol, a rapid trend occurred towards the normalization of the factors.