Gastroesophageal reflux disease has been very often in children and one of its most critical complications is the peptic esophagitis disease. The diagnosis of peptic esophagitis is obtained based on the endoscopic changes and the histologic features. The pressure reduction of the lower esophageal sphincter is one of the elements of the esophagitis pathogenesis. The pressure is related with the length of the esophageal abdominal segment, which can be measured by ultrasonography. The research presented in this paper aims to relate ultrasonographic measurements of esophageal abdominal segment length with endoscopic changes and with esophageal biopsy obtained from children with gastroesophagel reflux disease. We submitted 16 children with gastroesophagel reflux disease, between 10 and 156 months old (median 63.5 months old), to endoscopy and to esophageal biopsy. We verified the following results from endoscopy and biopsy: six of the 16 patients had endoscopic peptic esophagitis and, in five of these (six patients), the same diagnosis was confirmed by biopsy. Ten of the 16 patients had normal endoscopy, but the biopsy of four of these 10 patients showed histologic changes compatible with esophagitis. We observed no relationship between endoscopy and biopsy, when all degrees of histologic change were used to diagnose esophagitis. However, we found high relationship when the mild histologic changes were considered as only a consequence of the reflux. We verified the following results from ultrasonography: five of the six patients with endoscopic peptic esophagitis and all patients with esophagitis determined by biopsy (excluding those with mild histologic changes) had reduced esophageal abdominal segment length. In conclusion, we have found relationship between endoscopic changes and histologic features in the diagnosis of esophagitis and correlation between the reduced esophageal abdominal segment length and the presence of esophagitis.354292299Ballistreri, W.F., Farell, M.K., Gastro-oesophageal reflux in infants (1983) N Engl J Med, 309, p. 790Beiguelman, B., O teste do qui-quadrado (1994) Curso Prático de Bioestatística. 3.ed. Rev., pp. 59-93. , Beiguelman B. Ribeirão Preto, Revista Brasileira de GenéticaBoix-Ochoa, J., The physiologic approach to the management of gastric esophageal reflux (1986) J Pediatr Surg, 21, p. 1032Boix-Ochoa, J., Canals, J., Maturation of the lower esophagus (1976) J Pediatr Surg, 5, p. 749De Meester, T.R., Wernly, J.A., Bryant, C.H., Clinical and in vitro analysis of determinants of gastroesophageal competence: A study of principles of anti-reflux surgery (1979) Am J Surg, 137, p. 39Vandenplas, Y., Ashkenazi, A., Belli, D., Boige, N., Bouquet, J., Cadranel, S., Cezard, J.P., Tolboom, J., A proposition for the diagnosis and treatment of gastro-oesophageal reflux disease in children: A report from a working group on gastro-oesophageal reflux disease (1993) Eur J Pediatr, 152, p. 704Westra, S.J., Wolf, B.H.M., Staalman, C.R., Ultrasound diagnosis of gastroesophageal reflux and hiatal hernia in infants and young children (1990) J Clin Ultrasound, 18, p. 477Wienbeck, M., Barnert, J., Epidemiology of reflux disease and esophagitis (1989) Scand J Gastroenterol, 24, p. 7