The effect of preanesthetic administration of glycopyrrolate and cimetidine on gastric fluid pH and volume were studied. Forty patients scheduled for elective surgery were fandomly placed into two groups. Patients in group 1 were given glycopyrrolate intramuscularly (0.003 mg/kg) 30-60 minutes before induction of anesthesia, while group 2 patients received glycopyrrolate intramuscularly and 200mg of cimetidine intravenouly 2 hours before induction of anesthesia. Nasogastric tubes were placed and gastric pH and volume were measured. The results showed that patients in group 1 hade a medn gastric pH of 2.428±1.378. Twenty five percent of these patients had gastric contents with a pH of 2.428±1.378. Twenty five percent of these patients had gastric contents with a pH above 2.5 and a volume greater than 25ml. In contrast, group 2 patients had a mean gastric pH of 5.566±1.969, 85 percent had a ph above 2.5 and 15 percent had a volume greater than 25ml. These findings demonstrate that cimetidine markedly increases gastric pH. The authors recoment that patients reciving general anesthesia be given cimetidine preoperatively.