The aim of this study was to determine if erythromycin (EM), which is a potent motilin agonist, alters gastrointestinal motility in premature infants. Six infants who were born after 23-30 weeks gestation and weighed 825-1,408 g at birth were studied when 6-31 days old. Intraluminal pressure changes within the gastric antrum and proximal duodenum were recorded. We infused EM 0.75 mg/kg intravenously for 15 min and we compared gastric and duodenal contractions for 30 min between before and after the initiation of EM infusion. In these preterm infants the migrating complex was not present, and was not induced by EM. However, in all 6 infants EM increased nonpropagating antral clusters of contractions (p < 0.05). The antral motility index increased 4-fold (p < 0.05). We concluded that human premature infants have functioning motilin receptors.