From 1977 to 1984 six-hundred non selected patients with megaesophagus were prospectively examined through 722 endoscopies. 347 (57.8%) were men and 253 (42.2%) women the age ranged from 11 to 87 years (mean 45.7). 499 (90.2%) out of 553 patients had positive serologic test for Chagas' disease. 480 were non treated patients and 120 were previously treated. The following endoscopic findings were found: stasis esophagitis--15 (2.5%), reflux esophagitis--41 (6.5%), stenosis of esophagus--8 (1.3%), cancer of esophagus--5 (0.8%), hiatal hernia--3 (0.5%), esophageal varices--2 (0.3%), leukoplasia--1 (0.2%), duodeno-gastric biliary reflux--173 (30.4%), chronic gastritis--109 (18.2%), gastric ulcer--10 (1.8%), gastric polyp--2 (0.4%), gastric cancer--1 (0.2%), megabulbus--9 (1.6%), duodenal ulcer--10 (1.8%) and duodenitis--5 (1.9%). The cancer of esophagus and megaesophagus association in our results was lower than those reported by others; this may be due to the inclusion of early cases of megaesophagus in our patients. The high incidence of duodeno-gastric biliary reflux in the chagasic megaesophagus is claimed by the authors to be due to an antrum-pyloric-duodenal dyskinesia secondary to intrinsic denervation caused by Chagas' disease. Finally the authors recommend the endoscopy as a routine procedure in the megaesophagus in order to detect these associated morbid conditions.