To ascertain the prevalence of carcinoma in esophagi resected for high-grade dysplasia (HGD) using current criteria and to evaluate histologic features that may predict concurrent carcinoma, we studied specimens from 127 esophagectomies performed for HGD, or HGD "suspicious" for carcinoma (HGD/S) in Barrett mucosa. Corresponding biopsy specimens in 69 cases were reviewed and reclassified. Based on original diagnoses, carcinoma was present in 15 (17%) of 89 HGD and 28 (74%) of 38 HGD/S cases. By reclassification, only 1 (5%) of 21 cases with HGD had carcinoma in the resection specimen. Of 25 cases reclassified as HGD/S, 18 (72%) had carcinoma in the resection specimen, as did 17 (74%) of 23 reclassified as adenocarcinoma. With 1 additional select histologic feature, the risk of carcinoma was 39%; with 2 or more features, the risk increased to 83% to 88%. Based on current criteria, no more than 5% of esophagectomies performed for a biopsy diagnosis of Barrett HGD harbor carcinoma. When HGD/S is diagnosed based on certain additional features, carcinoma is found in nearly 40% of cases with 1 feature and more than 80% with 2 or more features. Our findings highlight the evolution of diagnostic criteria for Barrett dysplasia.