The effects of branched-chain amino acid (BCAA)-enriched nutrient mixture (nutrient-mixture) on the nitrogen metabolism and nutritional state were clinically investigated in 10 patients with liver cirrhosis. Nutrient-mixture-supplemented diet was prepared by adding 150 g nutrient-mixture daily to low-protein diet, and comparisons were made with a regular diet (control diet). Each diet supplied 2, 100 kcal energy and 80 g protein per day. Patients were given control diet for 2 weeks and thereafter treated successively with nutrient-mixture-supplemented and control diet each for 2 weeks. Nitrogen balance improvement and positive balance were observed during the feeding of nutrient-mixture-supplement-ed diet. The composition of nitrogen compounds in urine and the fecal nitrogen excretion did not alter during the test period. Plasma aromatic amino acid (AAA) concentrations decreased and BCAA/AAA molar ratios increased significantly during the 1st and 2nd week of nutrient-mixture-supplemented diet administration. Plasma methionine concen-tration also decreased in the 1st week. Plasma pre-albumin levels rose significantly during the 1st and 2nd week of nutrient-mixture-supplemented diet administration, and the number connection test improved significantly following the supplemented diet. These results suggest that the use of nutrient-mixture in the nutritional treatment of liver cirrhosis had no deleterious effects on nitrogen metabolism and is useful for the improvement of plasma amino acid imbalance and protein-energy malnutrition.