The effect on gastric pH and volume of 0, 6 and 10 ml.kg-1, of apple juice given 2.5 hours before surgery to children aged five to ten years was investigated in this prospective, randomized, single-blind study. Gastric contents were aspirated after induction of anaesthesia, and the volume measured. The pH of the gastric aspirate was then assessed using pH paper. Neither gastric volume nor pH immediately following the induction of general anaesthesia were significantly different among the three groups. Gastric volumes after 0, 6 and 10 ml.kg-1, of juice averaged (mean +/- SD) 0.45 +/- 0.31, 0.66 +/- 0.79 and 0.71 +/- 0.76 ml.kg-1, respectively; gastric pH averaged 1.7 +/- 0.6, 1.7 +/- 0.6 and 1.8 +/- 0.8, respectively. On the basis of questions asked immediately before induction of anaesthesia, patients who drank 6 ml.kg-1 of apple juice had decreased thirst and were less irritable and upset before anaesthesia than those who had not (P less than 0.05). It is concluded that drinking large volumes of clear apple juice 2.5 hours before scheduled surgery does not have a measurable effect on gastric volume and pH and may offer benefits such as improved patient comfort.