The effect of Pantethine (antioxidant) on chronic liver diseases, especially ethanol-induced, was investigated. Pantethine was administered for 12 weeks to 2 groups patients with chronic liver diseases : the one is alcoholic group of people who had drunk over 80 g of ethanol per day for more than 10 years and another is non-alcoholic group. The following results were obtained. 1) No noticeable effect of Pantethine on transaminase was found in both groups. 2) The value of γ-GTP tended to decline in alcoholic group when the dose of Pantethine was 6.0g Per day. 3) This drug was effective to the normalization of serum lipid, of lipid peroxides in plasma was not significantly changed in both groups. 5) There was not a remarkable side effect due to this drug.