The incidence of gastroesophageal reflux (GER) in infants has been shown to be dependent on different factors, e.g., position, feeding, age. Using continuous esophageal pH monitoring, we examined 30 asymptomatic (15 were 1.5-2.5 months old; 15 were 2.5-4.5 months old) and 20 symptomatic infants (1.5-4.5 months old) for GER. The occurrence of GER was analyzed in different periods of interest: awake, asleep, fasted, and postcibal periods. The increasing incidence of GER we reported previously in asymptomatic infants according to their age appeared to be due to an increased occurrence in the awake (and postcibal) periods. In symptomatic infants, however, the increase was noticed mostly during the sleep (fasted) periods as far as the reflux index, the duration of the longest reflux episode, and the number of reflux episodes of greater than 5 min are concerned.