Alcohol feeding to rats that were submitted to a jejunoileal bypass operation has been shown to result in liver damage being comparable with alcohol-induced liver disease in man. In the present study, a striking effect of free methionine consumption on histological liver injury, triglyceride accumulation, and energy-rich nucleoside content in the liver of rats with a jejunoileal bypass is demonstrated. The animals obtained 0, 30, and 120 mg of methionine in the control group and 0, 30, 120, and 240 mg in the alcohol- fed group per day and per kilogram of body weight for 12 weeks. Methionine was found to strongly improve the alcohol-induced histological changes in the liver. Triglyceride content of the liver was found to decrease in a dose- dependent manner with increasing methionine ingestion (from 255 ± 20.7 to 49.7 ± 6.1 μmol/g of protein in the control group and from 233 ± 17.3 to 42.1 ± 7.2 μmol/g of protein in the alcohol group). Hepatic adenosine triphosphate content increased significantly with higher methionine consumption (13.5 ± 0.8 vs. 26.9 ± 2.8 μmol/g of protein in the control group and 11.9 ± 1.4 vs. 20.5 ± 2.5 μmol/g of protein in the alcohol group), whereas no differences were found in the protein and DNA content of the liver. These results underscore the impairment of the transmethylation/transsulfuration pathway in the development of alcohol- induced liver diseases.