The physiologic similarities between the megaesophagus of Chagas' disease and idiopathic achalasia are well documented. Therefore, it would seem reasonable that comparisons of controlled trials of therapy for the more common Chagas' megaesophagus could be applied to idiopathic achalasia, where the paucity of cases makes such a controlled comparison difficult. We had the opportunity to study 18 patients with achalasia secondary to Chagas' disease. All of the patients were from the mid central states of Brazil, all had symptoms of dysphagia and radiographic documentation of dilated esophagus and abnormal peristalsis (Rezende Groups II and III), as well as positive serologic evidence of Chagas' disease. Perfused intraluminal manometric studies were performed on all patients. Resting sphincter pressures ranged from 20-35 mm./Hg., mean of 25 (normal 5-12 mm./Hg.) with aperistalsis. Patients were randomly dilated with either bouginage (44-55 ff catheter) or pneumatic dilator (4-4.5 kg./6.5 cm.2 x 2 min.). Although all patients reported symptomatic improvement several days after either procedure, repeat manometric tracings demonstrated no change in the sphincter pressure in the bouginage group. The pneumatically dilated group, however, demonstrated a decrease in sphincter pressure to normal levels (mean 12 mm./Hg.). Follow-up studies one year after the procedure confirmed the persistence of normal sphincter pressure in the pneumatically dilated group but no change, as well as return of initial symptoms, in the bouginage group.