To determine whether the gastric content pH of paediatric patients could be raised in an effort to decrease post-aspiration morbidity and mortality, the antacid sodium citrate (0.4 ml.kg-1) was given preoperatively to 25 patients aged 1 to 14 (6.0 +/- 3.5, mean +/- SD) years. Their gastric content pH was measured following induction of anaesthesia. These values were compared to those obtained from a control group (n = 20) ranging in age from seven months to nine (3.3 +/- 2.7) years. A gastric content pH value of greater than 2.5 was measured in 23 of the 25 patients who received sodium citrate. There were only two patients in the control group with a gastric content pH greater than 2.5, p less than 0.001, Fisher exact test. Only one child refused to take the medication. The administration of sodium citrate appears to be an effective method of raising the gastric content pH in paediatric patients.