Gastric perforation is a catastrophic, albeit uncommon, side effect of steroid treatment for premature infants with bronchopulmonary dysplasia (BPD). A reduction of intragastric acidity may protect against peptic ulceration. The effect of different doses of ranitidine, given as intravenous infusions, on intragastric acidity in premature neonates was therefore examined. Ten consecutive, enterally starved, infants receiving dexamethasone (0.6 mg/kg) for BPD were enrolled. Intragastric pH was continuously monitored on the day before steroid treatment and on the four following days, initially without H2 blockade and then using a continuous intravenous infusion of ranitidine at 0.031, 0.0625, and 0.125 mg/kg/hour. An infusion of 0.0625 mg/kg/hour of ranitidine was sufficient to increase and maintain gastric pH above 4; the authors therefore use this infusion during dexamethasone administration as possible prevention of gastric perforation.