A 31-year-old woman presented with progressive weight gain, facial acne, round facies, hirsutism, and secondary amenorrhea. Her plasma cortisol, urinary free cortisol, and plasma ACTH were elevated. CT scan of abdomen revealed bilateral diffuse adrenal enlargement. MRI of pituitary failed to identify a lesion. CT scan of chest revealed an 8 mm nodule in the lower lobe of the left lung. The diagnosis of ectopic Cushing's syndrome was made. The lung tumor was surgically removed. The tumor measured up to 1.5 cm in diameter. By light microscopy, a tumor with characteristic features of bronchial carcinoid was noted. Immunostains were positive for neuron-specific enolase, synaptophysin, chromogranin, low-molecular-weight keratin, ACTH, beta endorphin, corticotropin-releasing hormone, bombesin, alpha subunit, and somatostatin. Electron microscopy revealed an endocrine neoplasm. The secretory granules displayed great variation subdividing the endocrine neoplasm. The secretory granules displayed great variation subdividing the cell population into an undetermined number of phenotypes. In situ hybridization demonstrated positivity for pro-opiomelanocortin mRNA in the tumor cells. Postoperatively, plasma cortisol had fallen. The patient remained symptom-free one year later. The case presented here was regarded as a plurihormonal bronchial carcinoid associated with ectopic Cushing's syndrome. This unique plurihormonal bronchial carcinoid tumor produced three hormones, ACTH, CRH, and bombesin, that may have contributed to the patient's ectopic Cushing's syndrome.