Background: Mediastinum includes the vital organs like the heart the major respiratory passages and the major vessels due to this vicinity, the masses of this area with malignant or benign etiology or cause systemic diseases such as metastatic malignancies or granulomatous reactions can be potentially fatal.

Materials and Methods: According to the priority of the problem, a ten years comprehensive retrospectively study of mediastinal masses in children was conducted In children medical Center (Tehran University) from the points of view of incidence, clinical manifestations and diagnostic and treating ways. Results &

Conclusion: In our study there were 34 patients from 1992-2002 who were reviewed. No differences between boys and girls with mediastinal masses were observrd. The most prevalence age for mediastinal tumors was form 5-10 years (38%). The most prevalent sign was fever (53%) and the most common symptom was coughing (44.4%). Basesd on this research, mediastinal masses have been the most prevalent finding in chest radiography (53.8%). CT-Scan with double contrast was recognized as the most common and easiest ways for diagnosing masses. Anterior masses were the most common finding in our study (41.7%). Most of these masses were removed by surgery and the most common operation in our patients was thoracotomy and removing the masses (61.7%). Lymphoma was the most common masses (35.2%) and masses with neural orgins occupy the second grade. According to available documents and with regard to mean follow up of patients in 3.2 years the rate of survival was 54%.