Patients occasionally arrive in the operating suite chewing gum despite instructions to avoid oral intake for a specific number of hours before surgery. Some anaesthetists are hesitant to proceed with these patients fearing an increase in gastric volume and acidity. This study was undertaken to determine if gum chewing increased gastric volume and acidity. Seventy seven patients were recruited and informed consent obtained. Thirty-one patients who fasted overnight were randomly assigned either to serve as control (Group 1) or to chew sugarless gum prior to anaesthesia (Group 2). The remaining 46 patients fasted overnight but were given sugarless gum and allowed to chew it until immediately before induction of anaesthesia if they desired (Group 3). Volume and pH of gastric content were determined immediately after induction of anaesthesia and tracheal intubation. Results revealed mean values (range) of gastric volume for Group 1-26 ml (9-60), Group 2-40 ml (5-93), and Group 3-28 ml (4-65). Mean values for pH (range) were Group 1-1.8 (1.0-4.6), Group 2-1.6 (1.3-1.9), Group 3-1.7 (1.0-4.4). There was no difference between groups in terms of gastric volume or pH. In addition, there was no relationship between gastric content and the length of time from gum discard to induction or the length of time gum was chewed. In conclusion, the data suggest that induction of anaesthesia is safe and surgery does not need to be delayed if a patient arrives in the OR chewing sugarless gum.