A case of malignant paraganglioma arising from the posterior mediastinum and presenting with a chest wall metastasis is reported with immunocytochemical and ultrastructural documentation. The pathobiologic features of this rare disease are reassessed with a review of the literature. Cytoarchitectural features do not provide reliable information regarding malignant potential. However, evidence of local invasiveness at surgical exploration and/or lack of initial surgical control are likely to be associated with synchronous or metachronous metastatic disease. Although there are clinicopathologic differences warranting distinction between benign paragangliomas arising in the anterior and posterior mediastinal compartments, there is no apparent pathobiologic difference with regard to the malignant group.