Fibrosing mediastinitis is a rare entity usually caused by granulomatous disease. Most cases develop as a complication of histoplasmosis. Mediastinal involvement caused by tuberculosis most often produces focally enlarged lymph nodes, with diffuse mediastinal involvement a very unusual manifestation of disease. The authors describe a patient with extensive tuberculous fibrosing mediastinitis, in whom fibrotic masses produced compression of airways and vascular structures with resultant parenchymal changes.