AbstractA branched chain amino acid (BCAA) solution was infused for 2 weeks following major hepatic resection in patients with malignant tumors of the liver. The infusion caused a significant reduction in plasma concentrations of phenylalanine, tyrosine, methionine, and ammonia as compared with the control patients. The BCAA infusion also prevented a marked fall in the molar ratio of valine, leucine, and isoleucine to phenylalanine and tyrosine. No untoward effects of the treatment were found. Although further studies are necessary to determine an ideal dose of BCAAs from the viewpoint of nitrogen balance, the BCAA solution seems to be a useful nutri‐tional element after major hepatic resection if given with hypertonic glucose.