The serum concentration of ethanol and the activities of aspartate aminotransferase, alanine aminotransferase and gamma-glutamyltransferase (GT) in 40 male chronic alcoholics were determined on admission to hospital. The serum activities of the enzymes were highest in patients with established alcoholism for less than 5 years. The serum concentration of ethanol, however, was lowest among these patients and gradually increased with the duration of alcoholism. No correlation was found between the serum ethanol level and the activity of any of the enzymes. The duration of the current debauch, which was shortest in cases of long-standing alcoholism, showed a positive correlation with the S-GT activity.