The incidence of gastroesophageal reflux in recurrent croup was evaluated by a retrospective analysis of patients at the Children's Hospital of Michigan from 1986 to 1991. Sixty-six patients required hospitalization for recurrent croup during this 6-year period. Of the patients evaluated, 47% with recurrent croup had an additional diagnosis established of gastroesophageal reflux. In patients with three or more hospitalizations for croup, there was a 63% association with gastroesophageal reflux. Compared to all patients with recurrent croup, the patients with gastroespphageal reflux tended to be younger and had a shorter interval between episodes of croup. A prospective series of six cases of recurrent croup was seen in consultation. The diagnostic procedures involving lipid-laden macrophage quantitation, endoscopy, and gastroesophageal reflux scintiscans were utilized to establish the diagnosis of gastroesophageal reflux with tracheal aspiration. The results of these studies and the follow-up is discussed.