Pheochromocytoma was usually derived from adrenal medulla or chromaffin cells in or about sympathetic ganglia, and manifested several symptoms and signs by producing, storing, secreting catecholamine. This tumor frequently presented various symptoms such as paroxysmal or persistent hypertension, headache, sweating, palpitation. EKG abnormalities, myocarditis, cardiomyopathy, angina pectoris and myocardial infarction have been reported in cardiovascular systems. We experienced two cases of pheochromocytoma associated with myocardial infarction Two patients presented typical cardiac enzyme patterns and regional wall motion abnormalities on ehcocardiography which was compatible with acute myocardial infarction. However, these patients showed normal coronary artery on coronary angiograpy. Urinary excretion of catecholamine metabolites were elevated and pheochromocytoma was found on right adrenal gland. After the removal of pheochromocytoma, urinary excretion of catecholamine metabolities, regional wall motion abnormalities on echocardiography and blood pressure were normalized. (Korean J Med 57:357-363, 1999)