Pheochromocytoma may infrequently lead to dilated cardiomyopathy, which may reverse partially or completely after treatment. Progressive dyspnea, palpitations, and paroxysmal attacks of severe hypertension leading to cardiac failure had developed in a 25-yr-old woman. Chest radiography and echocardiography revealed a massive 4-chamber dilatation of the heart with an ejection fraction of 12%. Twenty-four-h urinary vanillylmandelic acid and metanephrine levels were elevated. Magnetic resonance imaging detected a large mass lesion in the right adrenal gland. Oral glucose tolerance testing revealed diabetes mellitus. Medical drug therapy with alpha-blocker, angiotensin converting enzyme inhibitor, beta-blocker, digoxin, and diuretic rapidly improved her cardiac condition. Repeat echocardiogram showed that the left ventricular function had improved substantially. The clinical condition of excess catecholaminemia (and thus, arterial hypertension and the abnormality of the glucose metabolism) subsided with complete resolution of the congestive heart failure following the surgical removal of the tumor. Evaluation for medullary thyroid carcinoma (MTC) revealed an elevated calcitonin level demonstrated by fine needle aspiration biopsy. There were no biochemical evidences for primary hyperparathyroidism. Multiple endocrine neoplasia 2 (MEN 2A) syndrome was diagnosed. An overwhelming secretion of catecholamine might cause severe cardiomyopathy and impair glucose metabolism, as evidenced by the improvement of both conditions following the medical treatment of catecholaminemia and surgical resection of the tumor.