Functioning extraadrenal paragangliomas represent more than 10% of all pheochromocytomas, occur at diverse anatomic locations, and are said to have a higher malignancy rate than intraadrenal pheochromocytomas. Sixty-six patients had surgery for catecholamine-producing paragangliomas between 1952 and 1992. Median follow-up was 8.8 years. Median age was 40 years (11-67 years); the male/female ratio was 29:37. Familial disease occurred in 9 patients (13.6%), and 10 patients (15.2%) also developed adrenal pheochromocytoma. Solitary paragangliomas occurred in 52 patients: 46 abdominal, 4 thoracic, and 2 head and neck. Fifty-three tumors developed in 14 patients with multiple paragangliomas: 38 abdominal and 15 thoracic. Of 28 patients with solitary tumors undergoing localization studies over the past 10 years accurate localization was achieved in 27. There was one operative death; 15 patients had persistent disease; and 50 were cured postoperatively. Of those cured, nine developed recurrence, disease-free survival being 86%, 80%, and 80% at 5, 10, and 20 years. Metastatic disease was found in 14 patients (21%), 7 of whom have died. An additional 10 patients (15%) had locally invasive disease, of whom 4 have died. Cause-specific survivals at 5, 10, and 20 years were 90%, 83%, and 72%. Risk factors for death from pheochromocytoma were tumor size > 5 cm (p = 0.0002), metastatic disease (p = 0.001), and tumor invasion (p = 0.0023). Cause-specific survival for patients with tumors > 5 cm was 59% at 15 years compared to 100% among patients with tumors </= 5 cm (p = 0.0003). Functional paragangliomas are frequently malignant and are associated with a high incidence of persistent or recurrent disease. Tumor size > 5 cm and the occurrence of invasive or metastatic disease are strong predictors of outcome. Most tumors are abdominal, and imaging is highly successful for localization.