A solitary fibrous tumor in the pleura has been reported occasionally, but extremely rare in themediastinum. The histogenesis of this tumor has been still in controverse, but recent studies paid attention to it a mesenchymal origin by the immunohistochemical and ultrastructural bases. A few cases, reported in the literature, suggest that the mediastinal solitary fibrous tumor occurs more commonly in adult and shows slightly higher incidence in women. Its aggressive behavior such as recurrence rate and distant metastasis, is more prominant than reported in solitary fibrous tumor of the pleura. No single histologic feature allows an assumption definite prognosis. Surgical resection of this tumor is usually curative although the recurrence or distant metastasis are reported in about half of the patients. This report is a case of solitary fibrous tumor in the mediastinum in a 16-year-old female patient.She underwent surgical resection and her postoperative result was satisfactory.