To evaluate the effect of positioning on behavior in infants with gastroesophageal reflux, 48 infants younger than 6 months of age (range 1.5 to 28 weeks, median 13.5) with reflux were positioned continuously prone (24 infants) or seated (24 infants) during a 120-minute postprandial period, during which behavior was monitored continuously. The prone position was associated with more sleep time, 83.5 (16 to 113) vs 43 (0 to 117) minutes, P = .01. This increase in sleep time in the prone position could be largely accounted for by a tendency toward a decrease in crying time, 19 (0 to 82) vs 38.5 (0 to 91) minutes, P = .07, which is expressed further by the significantly smaller number of prone than seated infants who cried longer than 30 minutes, P = .02. A parallel reduction in noncrying awake time in the prone vs the seated position was not significant: 15 (0-51) vs 31 (3 to 84) minutes, P = .13.