Blood glucose concentration was measured in 100 children immediately before and during surgery. These children were randomly assigned to receive either lactated Ringer's (LR) solution or 5% dextrose in lactated Ringer's (5%D/LR) intraoperatively as maintenance and replacement fluids. Blood samples were taken immediately after induction of anaesthesia and at 1/2, 1, 1.5, 2 and subsequent hours. Blood glucose concentration was assayed by a reflectance meter. None of the patients was noted to be hypoglycaemic pre- and intraoperatively. Intraoperative blood glucose concentration increased significantly (p < 0.05) from preoperative levels for both groups of children but the increase in those that received 5%D/LR was significantly greater (p < 0.05) than those who received LR. The number of children who were hyperglycaemic during surgery was also greater in those who received 5% dextrose in lactated Ringer's as their intraoperative fluid. These data suggest that lactated Ringer's alone is a safe and appropriate fluid for intraoperative fluid therapy in children.