Extra-adrenal paragangliomas and pheochromocytomas are rare but clinically important tumors, which produce, store, release, and metabolize catecholamines resulting in unexpected life-threatening effects. It is neither easy nor difficult to clinically diagnose these tumors despite the availability modern clinical methods because signs and symptoms such as recurrent episodes of paroxysmal hypertension and headache are nonspecific. Only a few cases of unexpected death in which the deceased had a non-diagnosed paraganglioma or pheochromocytoma have been reported. Death in these cases is usually sudden and occurs during emergency room care or during a major or minor abdominal operation, without prodromal symptoms. Death is considered to occur because of paroxysmal hypertension, cerebrovascular attacks, abrupt hemorrhage into the tumor parenchyma, or acute left ventricular failure. We report the case of a 73-year-old man who died 12 hours after undergoing decompression surgery for spinal stenosis. A medico-legal autopsy revealed that death in this case resulted from an undiagnosed paraganglioma around the abdominal aorta.