The effect of two weeks of total parenteral nutrition (TPN) on energy-rich phosphates, muscle water, electrolytes and free amino acids in skeletal muscle were determined in ten malnourished patients with gastric carcinoma. The total adenine nucleotide pool, phosphocreatine, creatine and glycogen were decreased before TPN, and only glycogen returned to normal after TPN compared with controls. Total muscle water and the intramuscular concentrations of sodium and chloride were initially increased and were not influenced by TPN. The total non-essential amino acids in muscle were decreased by 9 per cent, mainly due to a 15 per cent decrease in glutamine. The concentrations of free amino acids in muscle were not affected by two weeks of TPN. This study demonstrates disturbances in energy, water and amino acid metabolism in skeletal muscle of malnourished patients with gastric carcinoma, and that two weeks of TPN could not normalize these changes, except in the case of glycogen. The reason for this might be enzyme abnormalities due to adaptation to energy or protein deficit. A longer period of refeeding might therefore be necessary to improve peripheral metabolism in these patients.