Several case reports have emphasized that esophageal carcinoid tumors are associated with a poor prognosis. To expand our knowledge about the pathology and biologic behavior of these rare tumors, we reviewed the clinicopathologic and immunohistochemical findings of four cases of primary esophageal carcinoid. The age of the patients ranged from 48 to 82 years (mean 63 years; median 61 years). The lower segment of the esophagus was involved in two cases and the mid segment was involved in one case. The sizes of the tumors ranged from 0.3 cm to 3.5 cm. Two tumors were confined to the lamina propria and two invaded into the muscular wall. Two tumors appeared polypoid, whereas the remaining two were incidental findings and associated with adenocarcinoma arising in a background of Barrett esophagus. The adenocarcinoma was superficially invasive in one case, whereas it penetrated the muscular wall in the other. All four carcinoid tumors were immunoreactive with chromogranin and synaptophysin. There was focal expression of serotonin in two cases, glucagon in one case, and pancreatic polypeptide in one case. Endocrine cell hyperplasia was noted in both the Barrett esophagus and the invasive adenocarcinoma. One patient died secondary to postoperative pneumonia. Three patients are alive and disease free at 1, 6, and 23 years status post therapy. None of the patients had metastatic disease. These findings show that esophageal carcinoids are associated with a favorable prognosis. They arise in two settings: (1) a single large polypoid tumor or (2) an incidental finding and in association with adenocarcinoma arising in the background of Barrett esophagus. The presence of endocrine cell hyperplasia in the Barrett mucosa and the adenocarcinoma supports the hypothesis that these lesions arise from a common stem cell.