BACKGROUND Intraoperative amino acid infusion can attenuate the decrease in core temperature, but the metabolic effects are uncertain. METHODS Thirty-six healthy mongrel dogs undergoing ileectomy under general anesthesia were infused intraoperatively with normal saline or 18 compound amino acids at 6, 12, and 24 kJ·kg⁻¹·h⁻¹ (NS, 6-, 12-, and 24-kJ groups) and studied until 24 h after the operation. Blood glucose, plasma insulin, free fatty acids, and triglyceride concentrations were determined at 7 defined time points. Muscle aminograms, urinary urea, and 3-methylhistidine excretions were measured before and after the operation. RESULTS Blood glucose and plasma insulin increased amino acid dose dependently during the operation and in the early period after the operation. Free fatty acids were significantly lower in the 12- and 24-kJ groups compared with the NS group at the end of the operation. The negative nitrogen balance was alleviated dose dependently in the amino acid groups on operation day. The urinary 3-methylhistidine decreased significantly during the first 24 h after the operation in the 24-kJ group, while it increased in the other groups with the largest increase in the NS group. Basic, branched-chain, and aromatic amino acids in the vastus lateralis muscle increased dose dependently at the end of the operation in the amino acid groups. CONCLUSIONS Intraoperative amino acid infusion has the dose-dependent effects of increasing blood glucose, inhibiting fat mobilization and muscle protein breakdown.