Mediastinal fibrosis is pathologically characterized by chronic inflammation and fibrosis of mediastinal soft tissue. Mediastinal fibrosis is local expression of a family of systemic fibrosing syndroms. This can result in compression of adjacent mediastinal structures. Idiopathic fibrosing syndromes include retroperitoneal fibrosis, sclerosing cholangitis of the orbit and fibrosis of the thyroid gland(Riedel's struma). The cause of these disorders is obscure, in some instance there is an underlying malignancy, infection, history of drug ingestion, or trauma with retoperitoneal bleeding. Treatment of mediastinal fibrosis depends on structures involved by the fibrotic process. The disease is self limited in most case or improved by steroids uses. We experienced a case of idopathic solerosing mediastinitis with orbital fibrous dysplasia of unknown cause, which was confirmed by open lung biopsy, so reported it with a review of literature.