The liver plays a main role in the metabolism and storage of nutrients. A deficiency of nutrients, therefore, is often associated with liver diseases and may be caused by decreased storaged, abnormalities in metabolism or increased requirements for nutrients. It should be corrected by means of parenteral nutrition when enteral feeding is not available, especially in young infants who have minimal storage and maximal requirements for nutrients. For the purpose to establish an optimal parenteral nutrition in young infants with hepatic disorders, experimental studies have been performed. Ten obstructive jaundiced weanling rats with mild hepatic dysfunction have been fed intravenously for seven days. The two I. V. feeding regimens used in the series consisted of glucose and commercially available L-synthetic amino acids PROTEAMIN (E/N : 1.0, FAO/WHO : , 1963) or newly deviced L-synthetic amino acids FAH-01, made for the subjects. These two regimens provided 350 Cal/kg/day that was considered as "full-strength" by the preliminary studies using ten weanling rats with normal liver function. Although positive nitrogen balances were achieved in both groups of rats, all of the rats fed PROTEAMIN regimen markedly lost their weight and fairly well weight gains were shown in the other group of rats fed with FAH-01 regimen. The serum aminograms of the rats fed with PROTEAMIN regimen indicated marked elevation of His., Thr., and Pro., whereas the minimal abnormalities were detected in the serum aminograms in the rats fed with FAH-01 regimen. These results suggested that the composition of the amino acid solutions is very important to perform the optimal parenteral nutrition for the young infants with mild hepatic dysfunction.