The effect of eating on childhood gastroesophageal reflux (GER) is unclear. Twenty-eight asymptomatic children and 28 children with symptoms of GER were fed apple juice or milk-formula and observed for 3 hr postcibal. Distal esophageal pH was monitored continuously during this interval and used to quantitate the frequency and duration of GER. A period of frequent GER occurred for up to 2 hr after apple juice feedings in asymptomatic children, whereas symptomatic patients had frequent GER for longer periods. Compared to apple juice feedings, milk-formula feedings resulted in a decreased esophageal acidity for the first 2 hr. However, the type of feeding did not affect GER seen in asymptomatic children more than 2 hr postcibal. The frequency and duration of postcibal GER were not reduced by the upright position in either group. Effective medical treatment of symptomatic children did not eliminate the frequent GER within 2 hr of apple juice feedings, whereas the Nissen fundoplication usually eliminated all GER. The absence of GER episodes following apple juice correlated with the inability of most children to burp or vomit following antireflux surgery. Therefore, frequent GER for up to 2 hr after clear liquid meals is probably physiologic in children. The effective control of vomiting by medical or surgical therapy correlated best with a decrease in GER more than 2 hr postcibal.