From 1955 to 1985, 20 patients presented with a total of 22 extra-adrenal pheochromocytomas (2 had multiple tumors and 2 had a malignant extra-adrenal pheochromocytoma). There were 13 male and 7 female patients, and the highest incidence was in the second decade. Although most patients presented with symptoms typical of pheochromocytoma, several presented with unusual features related to the anatomical location, such as mediastinal mass (chest tumor), upper airway obstruction (neck tumor) or gross hematuria (bladder tumor). In 5 of 6 patients in whom plasma catecholamine levels were fractionated epinephrine levels were elevated. The most common tumor location was the superior para-aortic region (13 patients). In 16 patients the location of tumors was established before treatment. Computerized tomography (9 patients) was the most accurate imaging study for tumor localization. A total of 19 patients underwent complete excision of all pheochromocytomas. Postoperative followup information (median interval 120 months) was available for 15 of these patients. Three patients had recurrent pheochromocytoma that was treated successfully. One patient had essential hypertension. No patient had metastatic disease. The low incidence of malignancy suggests a benign course for extra-adrenal pheochromocytoma and represents a departure from the previously reported higher incidence of malignancy with extra-adrenal pheochromocytoma.