Iodine-131 metaiodobenzylguanidine ((131)I-MIBG) therapy is an effective treatment for patients with malignant paraganglioma for which surgical resection is not indicated. We performed high-dose (131)I-MIBG therapy on two patients with malignant paraganglioma and multiple bone metastases. The bone metastases were diagnosed by magnetic resonance imaging (MRI). Metastatic bone lesions were evaluated by whole-body (131)I-MIBG imaging and bone scintigraphy. Whole-body (131)I-MIBG imaging showed extensive metastatic bone lesions, whereas conventional bone scintigraphy did not. There was a remarkable discrepancy between (131)I-MIBG imaging and bone scintigraphy in the diagnosis of metastatic bone lesions of malignant paraganglioma in our two patients. High-dose (131)I-MIBG imaging may detect early stages of bone metastases, compared with bone scintigraphy, in patients with malignant paraganglioma.