Inclusion Criteria:

• Have a diagnosis of either adrenal pheochromocytoma or extra-adrenal paraganglioma by histological confirmation OR plasma-free metanephrines and 24-hour urine test for catecholamines/ metanephrines
• Disease is metastatic or has recurred following surgery
• At least one measurable lesion seen by computed tomography (CT) or magnetic resonance (MR) scan performed within 4 weeks prior to the first dose of study drug
• At least one known tumor site is also seen on Ultratrace iobenguane I 131 scan
• Provide written informed consent and are willing to comply with protocol requirements
• Are at least 18 years of age
• If female, then not of childbearing potential as documented by history (e.g., tubal ligation or hysterectomy) or is post menopausal with a minimum 1 year without menses
• If female of childbearing potential, has a negative serum b-HCG pregnancy test within 48 hours prior to receiving iobenguane I 131
• Females who agree not to become pregnant and males who agree not to father a child during the 1 year period following the therapeutic dose of Ultratrace iobenguane I 131. Both females and males must use an acceptable method of birth control during the first year following the therapeutic dose of Ultratrace iobenguane I 131.

Exclusion Criteria:

• Females who are nursing
• Active CNS lesions by CT/MR scanning within 3 months of study entry
• New York Heart Association class III-IV heart failure
• Received any previous systemic radiotherapy within 6 months of study entry
• Administered prior whole-body radiation therapy
• Received external beam radiotherapy to greater than 25 percent of bone marrow
• Administered prior chemotherapy within 30 days of study entry
• Karnofsky performance status is less than 60
• Platelets are less than 100,000/uL
• Absolute neutrophil count (ANC) is less than 1,500/uL
• Serum creatinine is greater than 1.5 mg/dL
• Total bilirubin is greater than 1.5 times the upper limit of normal
• AST/SGOT or ALT/SGPT is greater than 2.5 times the upper limit of normal
• Has received a therapeutic investigational compound and/or medical device within 30 days before admission into this study
• Has any medical condition or other circumstances which would significantly decrease the chances of obtaining reliable data, achieving study objectives, or completing the study and/or post dose follow-up examinations
• Is determined by the Investigator that the patient is clinically unsuitable for the study.
• Has received a medication which inhibits uptake of iobenguane I 131:
• phenothiazines or decongestants within 2 weeks prior to enrollment; or,
• a tricyclic antidepressant within 6 weeks prior to enrollment.