BACKGROUND Preoperative fasting is a major cause of perioperative discomfort in paediatric anaesthesia and leads to postoperative insulin resistance, thus potentially enhancing the inflammatory response to surgery. Addressing these problems by preoperative carbohydrate intake has not been a well-defined approach in children. METHODS We randomised 120 children scheduled for gastroscopy under general anaesthesia to either a control group of standard preoperative fasting or a study group receiving a carbohydrate beverage (PreOp™; Nutricia, Erlangen, Germany). Their stomach contents were aspirated endoscopically, and the volume and pH measured. Perioperative discomfort was evaluated using, among other parameters, an observational pain scale in ≤4-yr-olds and a VAS in >4-yr-olds. The investigators doing the endoscopies and outcome evaluations were blinded to the study group allocation. RESULTS Compared with fasting, carbohydrate loading was associated with significantly less gastric content (P=0.01), fewer patients experiencing postoperative nausea (P=0.028), with no significant difference in postoperative vomiting. High preoperative VAS scores (>5) were recorded for only one child in the carbohydrate group vs five children in the fasting group. Bowel cleansing for simultaneous colonoscopies (n=61) made no difference to any of the intergroup findings. CONCLUSIONS Preoperative carbohydrates can reduce nausea and gastric content, the latter being a surrogate parameter for the risk and severity of gastric aspiration into the lungs during anaesthesia. Our study adds knowledge for preoperative fasting guidelines in paediatric anaesthesia. BACKGROUND DRKS00005020.