BACKGROUND Thymic neuroendocrine carcinoma (carcinoid) is rare. Here we present four cases of this unusual neoplasm to provide more clinical, radiologic, and prognostic data. MATERIALS AND METHODS Four male patients with an average age of 44 years (range 27-63) were identified as having thymic neuroendocrine carcinoma and were reviewed retrospectively. RESULTS One patient had Cushing's syndrome with elevated serum ACTH. Three others were asymptomatic with normal laboratory findings, one case was associated with MEN type 1. All underwent complete resection along with invaded adjacent structures. Local recurrence developed in two patients at 45 and 98 months after the initial excision. Both patients died at 90 and 105 months, respectively. The other two patients are alive and have been disease-free for 27 and 120 months, respectively. CONCLUSIONS Thymic neuroendocrine carcinomas have a rather poor prognosis based on their tendency to recur and metastasize many years after the initial operation. Therefore, prolonged follow-up is essential for these tumors.