Branched-chain amino acid (BCAA: Leu, Ile, and Val) mixture has been used for treatment of hypoalbuminemia in patients with decompensated liver cirrhosis in Japan. It has been known that BCAA, especially leucine, activates mTOR signals and inhibition of protein degradation results in promoting protein synthesis in vitro. Furthermore, leucine activates glycogen synthase via mTOR signals in L6 cell, but not hepatocyte, and it has been shown that leucine improved glucose metabolism in normal and cirrhosis model rats. In this review, it will be proposed about the pharmacological activity of branched-chain amino acids, mainly leucine, on tissue specificity of cirrhotic disease. (C) 2003 Elsevier Inc. All rights reserved.