Sclerosing mediastinitis is excessive production of fibrous tissue in the mediastinum. Its most common manifestations, widening of the mediastinum and superior vena caval obstruction, are the only roentgenographic findings generally recognized to be associated with this disease. Analysis of 29 cases of sclerosing mediastinitis and review of the literature reveal that compression of mediastinal organs by constricting bands of collagen may cause various roentgen manifestations including bronchial or tracheal obstruction leading to atelectasis or obstructive pneumonitis, pulmonary venous obstruction, pulmonary artery obstruction, esophageal obstruction and nerve entrapment. The most common abnormality seen on the chest roentgenogram, mediastinal widening, is usually superior and especially right paratracheal in location. Superior vena caval compression is smooth and tapered rather than irregular as in malignant disease. Pulmonary venous and arterial obstruction may cause cor pulmonale and death, although the other manifestations are usually not life-threatening. The most common causes of sclerosing mediastinitis are generally considered to be granulomatous diseases, especially histoplasmosis, although many other causes have also been suggested. The disease may be regarded as an inappropriate response to one of several stimuli.