Between January 1987 and December 1990, 293 upper GI endoscopic procedures were performed in 219 neonates < 1 month of age. No lesion was found in 57 cases (26%; group 1), whereas esophagitis was present in 158 cases, alone in 45 cases (20.6%; group 2) and associated with gastritis in 113 cases (51.8%; group 3). The association of esophagitis with gastritis seems to be a specific feature of neonates and not older children. The presence of gastritis with esophagitis suggests that a primary peptic mechanism is unlikely to explain all endoscopic findings, although the presence of such a mechanism secondary to esophagitis could contribute to the esophageal lesions. Acute fetal distress was more frequent in group 3 than in the other groups. Symptoms associated with endoscopic lesions in groups 2 and 3 were, respectively, malaise (38 and 42%), hematemesis (4 and 35%), frequent regurgitation (45 and 26%), and difficult feeding and/or failure to thrive (26 and 24%). In Group 3, minor symptoms often led to the diagnosis of severe mucosal lesions, and antireflux therapy elicited prompt relief of clinical symptoms. The causes of neonatal esophagogastritis remain unknown. Wide use of endoscopy in the presence of discrete clinical abnormalities is likely to considerably improve the clinical condition of some children in their first days of life.