Pheochromocytomas arise from chromaffin tissue, usually in the adrenal medulla, and are a cause for curable hypertension. Nearly all patients with this tumor are symptomatic, the most common symptoms being headache, palpitations and inappropriate perspiration. Diagnosis is confirmed by finding high levels of plasma catecholamines or increased excretion of catecholamine metabolites (metanephrines, vanillymandelic acid) in the urine. Localization of tumors(s) is important for the surgeon and is accomplished by CT scan, <sup>131</sup>I-metaiodobenzylguanidine scintiscans or abdominal aortography. Treatment is surgical extirpation by an experienced team after depleted plasma volume has been replenished. Ten percent of tumors are malignant, 10% are bilateral in the adrenal medullae and 10% are extra-adrenal.