Two hundred twenty-three patients underwent upper gastrointestinal endoscopy and biopsy. Correlation of endoscopic and histological findings revealed that a normal gastric and duodenal mucosa could be correctly diagnosed endoscopically in about 80 and 88% of cases, respectively. Duodenitis was diagnosed correctly in 83% of cases; however, the correct endoscopic recognition of gastritis was achieved in only about 50% of the cases. Better results were achieved in "anastomitis," in which the endoscopic diagnosis was correct in 90% of cases. This study supports the view that endoscopy alone should not be relied upon in the diagnosis of gastritis or duodenitis.