BACKGROUND: Elevations in blood lactate levels have been associated with poor postoperative outcome. The aim of the present study was to determine if preoperative supplementation with branched-chain amino acids (BCAA) decreases postoperative blood lactate levels in patients undergoing pancreatoduodenectomy. METHODS: The cases of 223 consecutive patients who underwent pancreatoduodenectomy were retrospectively reviewed. Postoperative blood lactate levels in patients who were treated with BCAA supplementation before pancreatoduodenectomy (December 2011-December 2014) were compared with levels in patients who were not pretreated (January 2008-November 2011). RESULTS: Postoperative lactate levels were significantly lower in patients who received preoperative BCAA supplementation than in patients who did not (2.6 vs 3.1 mmol/L, P = .005), although preoperative blood lactate levels were statistically equivalent between the groups. In the univariate analysis, preoperative BCAA supplementation, preoperative lactate levels, operation time, and postoperative glucose levels were associated with postoperative lactate levels. A multiple regression analysis was performed among the 4 factors, and the preoperative use of BCAA supplementation was independently correlated with postoperative lactate levels ( P = .046). CONCLUSIONS: Preoperative BCAA supplementation decreased postoperative blood lactate levels. These results suggest that preoperative BCAA supplementation may help patients recover after surgery.