AbstractTotal parenteral nutrition can be used to overcome amino acid imbalance in cancer patients. Because there is little documentation of treatment for amino acid imbalance in patients with hepatocellular carcinoma (HCC), we designed a study 1) to compare tissue levels of amino acids between HCC and the adjacent liver and 2) to determine which serum amino acids correlate to tumor volume. A significant elevation of methionine and a significant decrease of glycine and cystine were observed in HCC compared with adjacent liver tissue, and a significant correlation was found between tumor volume and serum methionine levels (x =‐0.636, p<0.01). Thus the tumor tissue competes successfully with host tissue for nitrogen substrates, particularly methionine, and an accelerated protein synthesis in HCC consumes large amounts of these amino acids. The possibility of methionine‐depleted treatment could be considered for patients with HCC.