The influence of branched chain amino acids and lipid on liver regeneration was examined after two-thirds hepatectomy in rats. Elemental diet (ED) as components of enteral nutrition was given through the gastrostomy tube. The rats were divided into four groups according to the amounts of branched chain amino acids (BCAA) and lipid in the diet as follows: ED-I; BCAA 27%, Cal/N ratio: 74, ED-II; BCAA 37%, Cal/N ratio: 95, ED-III; BCAA 37% + lipid emulsion, Cal/N ratio: 99, ED-AC; commercially available elemental diet. The degree of liver regeneration of these groups of rats were compared with that of the control rats which were fed per os ad libitum. The liver regeneration rate of each group was as follows: ED-I; 59%, ED-II; 88%, ED-III; 92%, ED-AC; 79%, the control group; 89%. Remarkable fatty deposits were microscopically observed in each liver of ED-I, II and AC groups. Fatty change in the liver of ED-III group was minimum. The observation indicates that administration of branched chain amino acid enriched elemental diet and lipid emulsion is effective for regeneration of the liver after partial hepatectomy.