Chronic sclerosing mediastinitis is a rare disease of unknown etiology, pathologically characterized by chronic inflammation and fibrosis of mediastinal soft tissue. The process is often progressive and can occur either focally or diffusely throughout the mediastinum. This can result in compression of adjacent mediastinal structures, most commonly the low-pressure superior vena cava but also the pulmonary artery and vein, trachca and bronchi, esophagus and can result in a variety of functional and roentgenographic manifestation and occasionally death. We experienced a case of chronic sclerosing mediastinitis of unknown cause, which was confirmed by biopsy with thoracotomy, so reported it with a review of literature.