Few disorders of endocrine function are so sudden and dramatic in their presentation as those caused by a pheochromocytoma. This chromaffin cell tumor arises within the adrenal medulla or within the sympathetic nervous system and causes wide fluctuations in blood pressure, tachydysrhythmias, and manifestations of intense anxiety. The patient experiences explosive paroxysms of catecholamine overload. The diagnoses of accelerated hypertension or panic disorder often are prematurely adopted. The condition kills, with deaths primarily attributed to irreversible cardiovascular and end-organ damage caused by profound hypertension. For those with a pheochromocytoma, the disorder caused by the tumor is a terrifying constellation of symptoms. Although pheochromocytoma is rare, it must be considered in the treatment of any patient with sudden, extreme hypertension and accompanying hypermetabolism. A cure is possible, but only with early diagnosis and treatment.