A 63-year-old man was admitted to Sendai Red Cross Hospital complaining of chest and back pain associated with Cushing's syndrome. Based on the abnormally high levels of ACTH, cortisol, and CRH in plasma the patient was suspected of having ectopic ACTH syndrome. Histological examination of an extirpated rib and pleural tumor led to the diagnosis of atypical carcinoid tumor, with ribbon and festoon formation, immunoreactivity to ACTH, NSE, Chg-A, and argyrophilia in the tumor cells. Anti-cancer chemotherapy was not effective, and the patient died within a year after the onset of Cushing's syndrome. An autopsy revealed that the patient had an ACTH- and CRH-producing thymic carcinoid with metastases to many organs. The pituitary was atrophic with Crooke's hyaline change. There were many CRH-positive cells in the paraventricular nuclei of the hypothalamus, where no remarkable pathologic changes were seen.