The PACMAN trial is a multicenter, randomized, controlled, double-blind, two-arms study. 1022 patients undergoing major surgery (duration >90 minutes and one or more risk factor of postoperative complication) are randomized to dexamethasone (0.2mg/kg at the end of the surgery and at day1) or to placebo. The primary outcome is a composite outcome of major postoperative complication during 14 days after the surgery.