Previous studies have shown that duodenal motility patterns differ in preterm and term infants, but antral motor activities were not compared. Using a validated, low-compliance, continuous-perfusion, neonatal manometric system, antral and duodenal motility was studied in 19 preterm and nine term infants. Antral motility consisted of isolated single contractions and clustered phasic contractions in term and preterm infants. There were no differences in the occurrence or amplitude of antral activity between the two groups of infants. Thus, there was no change of antral motor activity with advancing gestational age. As has been shown in other previous studies, however, intestinal motor characteristics were more immature in preterm than term infants; clustered phasic contractions occurred more frequently (P less than 0.02) and were of shorter duration (P less than 0.02) and lower amplitude (P less than 0.005). Duodenal clusters were significantly less common, while their amplitudes were significantly increased with increasing gestational age. The proportion of antral clusters that were temporally associated with duodenal activity was significantly lower in preterm infants than in term infants (P less than 0.001). Moreover, the degree of association of antral and duodenal activity increased significantly with gestational age (r = 0.5, P = 0.006). These data show that fasting antral motor activity per se is comparable in preterm and term infants; they also suggest that the temporal association of antral and duodenal activity develops in association with progressive changes in duodenal motor activity in the preterm infant.