A 35-year male patient with clinical and biochemical manifestations of severe hypercorticism was thought to have Cushing's syndrome of pituitary origin. However, the surgically removed pituitary adenoma was not confirmed by pathological examination. There was no improvement after transsphenoidal microsurgery Chest CT scan showed a small mass located at the upper-lobe of the right lung. This tumor (1.8 x 1.0 x 1.0 cm) was removed and one course of radiotherapy with linear accelerator was given. Remission was achieved clinically and biochemically after these therapies. The diagnosis of bronchial carcinoid was confirmed by pathological findings. Metastasis of a lymph node was also proved. The tumor cells was found to contain ACTH and related peptides with radioimmunoassay, immunocytochemistry and electron microscopy. Gel filtration of the tumor extracts showed molecular heterogeniety of ACTH related peptides and that the big-form were in large percentage.