We examined the effect of taurine depletion on hepatic sulfur-containing amino acid metabolism and carbon tetrachloride-induced acute liver injury. Mice were supplemented with beta-alanine (3%) in drinking water for one week. beta-Alanine intake significantly reduced hepatic taurine levels, but did not influence S-adenosylmethionine, S-adenosylhomocysteine, glutathione levels or methionine adenosyltransferase activity in liver. However, hepatic cysteine levels were significantly elevated by beta-alanine administration. Hepatotoxicity caused by carbon tetrachloride (50 microl/kg, ip) in mice fed beta-alanine was decreased, as determined by changes in serum aspartate aminotransferase, alanine aminotransferase and sorbitol dehydrogenase activities. Hepatic glutathione and taurine levels after a carbon tetrachloride challenge were markedly increased by beta-alanine exposure. The results suggest that enhanced availability of cysteine for synthesis of glutathione and/or taurine may account for the hepatoprotective effects of beta-alanine against carbon tetrachloride-induced acute liver injury.