Tragically as many as 50% of pheochromocytomas are discovered at autopsy, mainly because the diagnosis of this neuroendocrine tumor was not considered. Missing the diagnosis almost invariably results in devastating cardiovascular complications or death. Clinicians must always think of pheochromocytoma whenever evaluating a patient with sustained or paroxysmal hypertension or any manifestations suggesting hypercatecholaminemia. Very rarely, familial pheochromocytomas may cause no hypertension, symptoms, or signs. But biochemical testing can always establish the presence or absence of a pheochromocytoma, and localization with magnetic resonance imaging, computed tomography, or 131I or 123I-MIBG is almost always possible.