BACKGROUND: To identify the gastric pH of gastric carcinoma patients after more than 8 hours of fasting and ascertain the antisecretory effects of H2-receptor antagonists, the gastric volume and pH of 41 gastric carcinoma patients was checked immediately after the induction of inhalational general anesthesia (endotracheal intubation). METHODS: The patients were divided randomly into two groups: the control received IV normal saline as a placebo and the famotidine group received IV famotidine as a premedicant 1 to 2 hours before the induction of anesthesia. Immediately after the induction of anesthesia, the gastric contents were aspirated blindly with a 60 ml syringe. Fisher's exact test was used to compare the percentage of patients 'at risk' between the two groups in relation to their pH and volumes. RESULTS: The percentage of patients 'at risk' (volume > 0.4 ml/kg and pH < 2.5) of acid aspiration pneumonitis in the control and famotidine groups was 8.7% and 5.6%, respectively, which was 30 77% lower than for patients with no premedication, as observed in other studies. In the present study, the difference in percentage of patients 'at risk' between the two groups was not statistically significant. CONCLUSIONS: The gastric carcinoma patients exhibited a higher gastric pH when fasting and a lower risk of acid aspiration pneumonitis relative to their gastric contents. The effect of famotidine on lowering gastric acidity and volume in gastric carcinoma patients was rather weak. Accordingly, the routine use of H2-receptor antagonists to decrease gastric secretion in gastric carcinoma patients should be reevaluated.