Background & Aims Barrett's esophagus is associated with adenocarcinoma of the esophagus. The aim of this study was to find the prevalence of Barrett's esophagus in patients with adenocarcinoma of the esophagogastric junction. Methods Consecutive, freshly resected surgical esophagogastrectomy specimens were examined, and multiple histological sections were made around the tumor periphery. Barrett's esophagus was defined as specialized columnar epithelium above the esophagogastric junction. Tumors centered ≤2 cm from the junction were defined as junction cancers. Results Barrett's esophagus was found in 9 of 9 (100%) esophageal adenocarcinomas compared with 0 of 8 (0%) squamous carcinoma controls (P ⩽ 0.001). Ten of 24 (42%) junction adenocarcinomas had a Barrett's esophagus. A Barrett's esophagus was found in 8 of 12 (67%) junction cancers ≤6 cm in length but only 2 of 12 (17%) larger tumors (P ⩽ 0.05). Barrett's esophagus was significantly associated with junction tumors <6 cm compared with squamous carcinoma controls (P ⩽ 0.02). In 5 specimens with junction cancer, the length of Barrett's esophagus was <3 cm, and in 5 specimens it was ≥3 cm. Specialized epithelium was often found below the esophagogastric junction in controls. Conclusions Adenocarcinomas of the esophagogastric junction are associated with short and long segments of Barrett's esophagus. Larger cancers probably overgrow and conceal the underlying specialized columnar epithelium from which they arise.