OBJECTIVE To determine the feasibility and effects of preanesthetic rectal famotidine on gastric fluid pH and volume in pediatric patients. METHODS Randomized, prospective, double-blind, controlled study. METHODS Operating room at a medical center. METHODS Eighty patients undergoing minor surgery under general anesthesia randomly allocated to one of two groups. METHODS Thirty-four patients in Group 1 were given 0.5 mg/kg of diazepam rectally 30 to 120 minutes before anesthesia induction. Thirty-eight patients in Group 2 received 1 mg/kg of famotidine, a new histamine (H2) blocker, and 0.5 mg/kg of diazepam through the same route. Six patients in Group 1 and two patients in Group 2 were excluded from the study due to gastrointestinal (GI) disorders. RESULTS Patients with gastric pH less than 2.5 or volume of gastric contents greater than 0.4 ml/kg were considered to be at risk for pulmonary aspiration. Thirty-five (92%) of the Group 2 patients had gastric contents with pH greater than 2.5 and gastric volume less than or equal to 0.4 ml/kg. Only 13 (38%) of the patients in Group 1 had similar gastric pH and volume. Rectal administration did not cause the children pain, and no anorectal problems of famotidine were detected. CONCLUSIONS Famotidine 1.0 mg/kg administered rectally 30 minutes prior to general anesthesia appears to result in a satisfactory increase in gastric pH.