OBJECTIVE To determine the incidence and predisposing factors leading to postoperative hypophosphatemia after major hepatic surgery and the consequences of this electrolyte abnormality. METHODS A retrospective study. METHODS A university tertiary care referral center. METHODS Thirty-five consecutive patients undergoing either major hepatic resections or cryosurgery from July 1994 through January 1997 were retrospectively reviewed for the occurrence of hypophosphatemia and postoperative complications. METHODS Prolonged ventilatory support, intensive care unit and hospital stays, and the incidence of postoperative complications. RESULTS The overall incidence of hypophosphatemia in our series was 21 (67%) of 35 with a mortality rate of 1 (2.8%) in 35. Mean operative time, estimated blood loss, partial vascular occlusion time, and transfusion requirements were similar between the hypophosphatemic and the nonhypophosphatemic groups. The presence of postoperative complications was significantly greater in the hypophosphatemic group (17 [80%] of 21) vs the nonhypophosphatemic group (4 [28%] of 14) (P<.05). The incidence of antacid use in the hypophosphatemic group (14 [66%] of 21) was significantly higher than the use in the nonhypophosphatemic group (2 [14%] of 14) (P<.05). CONCLUSIONS Hypophosphatemia commonly occurs in major hepatic procedures. The presence of moderate hypophosphatemia is associated with the use of antacid therapy but no other perioperative or operative variables. The occurrence of hypophosphatemia correlates with an increased incidence of postoperative complications. Awareness of this entity can direct aggressive replacement of phosphates and avert the occurrence of severe hypophosphatemia and associated complications.