We report a case of adrenocorticotropic hormone (ACTH)-independent macronodular adrenocortical hyperplasia (AIMAH). A 54-year-old Japanese man was admitted to our hospital for further examination of obesity and hypertension. Endocrinological studies showed that plasma cortisol was high (22.5 micrograms/dl) without diurnal rhythm, and plasma ACTH was low. Two or 8 mg of dexamethasone did not suppress the plasma cortisol levels. Abdominal computed tomography revealed nodular hyperplasia of bilateral adrenal glands. Adrenal scintigraphy showed the positive uptake of 131I-adosterol to bilateral adrenal glands. Brain magnetic resonance imaging revealed no abnormalities. He was diagnosed as having Cushing's syndrome with bilateral adrenal hyperplasia, and bilateral adrenalectomy was performed. Left and right adrenal glands were 52 g and 35 g, respectively, and were occupied by yellow nodular lesions. Histologically, hyperplastic lesions were composed of clear cells. Finally he was diagnosed with AIMAH.