This report describes adenocarcinoma in patients with Barrett's esophagus (BE) and adenocarcinoma of the esophagogastric junction (EGJ) and the gastric cardia. Definitions, frequency, and general features of both conditions are described. The macroscopic features and microscopic findings are detailed for invasive adenocarcinoma and superficial (early) adenocarcinoma. Prognosis and follow-up are evaluated using flow cytometry as a factor of prognosis. Precancerous conditions and etiological factors are discussed. In addition, primary adenocarcinoma of the lower esophagus not associated with BE is considered. The precancerous lesions and precancerous markers in BE and in the cardia are examined, including type of dysplasia, histochemical study, and other lines of research.