Plasma amino acid levels were determined in 23 patients in comparison with 16 normal subjects and 17 patients with liver cirrhosis. Patients with hepatocellular carcinoma had elevated levels of the aromatic amino acids and lowered levels of the branched-chain amino acids, as seen in liver cirrhosis; however, they had lowered levels of alanine and glutamine as compared with normal subjects and with liver cirrhosis patients. Following treatment with intraarterial chemotherapy and/or transcatheter arterial embolization, plasma levels of alanine and glutamine recovered. These results suggest that the consumption of alanine and glutamine increase in hepatocellular carcinoma.