In a double-blind, placebo controlled study of 10 infants with upper gastrointestinal motor disorders, metoclopramide (1 mg/kg, intravenous) but not bethanechol (0.075 mg/kg, subcutaneous), significantly increased the fractional rate of gastric emptying following a 5% glucose meal. Infants were tested on 3 consecutive days with a phenol red dye-dilution technique which, if combined with acid titration of gastric samples, permits simultaneous measurements of gastric volume, fractional emptying rate, fluid output, and acid output. Metoclopramide increased the fractional emptying rate in eight of 10 infants (mean +/- SE increasing from 4.6 +/- 0.6 to 7.3 +/- 1.0%/min, p less than 0.02). Neither drug altered gastric acid secretion, but metoclopramide significantly increased gastric fluid output (mean +/- SE increased from 3.5 +/- 0.6 to 6.5 +/- 1.4 ml/min, p less than 0.02). No undesirable side effects or complications occurred during testing. We conclude that trials are warranted to assess the clinical efficacy of metoclopramide in infants with nonobstructive causes of delayed gastric emptying.