In our study, we evaluated whether the combination of two endoscopic abnormalities in the duodenum (the "mosaic" appearance and loss of duodenal folds) is significantly associated with duodenal villous atrophy secondary to celiac sprue in adults. Fourteen patients referred for esophagogastroduodenoscopy for suspected celiac sprue and 146 for suspected peptic disease were enrolled in the study. At least one of the two endoscopic duodenal abnormalities was observed in all 10 untreated celiac patients but in only one of the dyspeptic patients. The sensitivity and specificity were 100 and 99.3%, with positive and negative predictive value of 90.9 and 100%, respectively. Such good results suggest that duodenal endoscopy can be a screening procedure for celiac sprue in patients who are undergoing endoscopy for other reasons.