We present a case of aldosterone-secreting adrenocortical carcinoma with concomitant myelolipoma. To the best of our knowledge, this is the first such reported case. The patient was a 43-year-old man with severe hypertension. Clinical workup revealed an increased serum aldosterone level, hypokalemia, and metabolic alkalosis, and a left adrenal mass was found on computed tomography. The patient underwent a unilateral adrenalectomy, which led to improvement in blood pressure, the serum potassium level, and aldosterone concentration. The tumor weighed 70 g and measured 5.0 cm. On microscopic examination, we found necrosis, focal cytologic atypia, diffuse eosinophilic cells comprising more than 75% of the tumor, 5 to 7 mitotic figures per 50 high-power fields, rare atypical mitosis, and venous invasion. At the periphery of the tumor but within the capsule, microscopic areas of myelolipoma were seen. Ki-67 staining was positive in 20% of the tumor cells. Although rare, aldosterone-secreting carcinoma associated with myelolipoma should be included in the differential diagnosis of adrenal gland masses.