In 14 patients with cirrhosis of the liver and portal-systemic shunts the effect of a branched-chain amino acid-enriched elemental diet on portal systemic encephalopathy, routine laboratory parameters and plasma amino acids was investigated. In addition to the standard therapy including protein restriction (40 g/day) the patients received 44 g of an amino acid-protein mixture containing 30% of branched-chain amino acids and placebo over 3 months in a crossover regimen. Plasma valine and leucine increased significantly, whereas all other amino acids, including the ratio (formula: see text), remained unchanged. The electroencephalogram, number connection test, clinical state and laboratory parameters were not influenced by therapy with branched-chain amino acids. Thus, orally administered branched-chain amino acids probably have no influence on hepatic encephalopathy but are an adequate source of nitrogen in patients with cirrhosis of the liver.