Primary mediastinal malignancies are rare tumors and can originate from any mediastinal organ or tissue such as thymic, neurogenic, lymphatic, germinal, ormesenchymal. The authors reviewed all cases of primary pediatric mediastinal masses diagnosed over a 25-year period to determine the pattern of presentation, the histology, and the outcome of the surgical treatment. In this study, 120 primary pediatric mediastinal mass cases diagnosed between 1985 and 2011 are retrospectively evaluated according to their age, sex, symptoms, anatomical location, surgical treatment, and histopathological evaluation. The median age of the patients was 5.8 years. There were 34 benign and 86 malign tumors. Thirty patients were asymptomatic. Common symptoms in the patients were cough, dyspnea, fatigue, fever, abdomen pain, back pain, and neurological symptoms. According to their origins, they were presented as neurogenic tumors (38.3%), lymphomas (18.3%), undifferentiated sarcomas (15%), germ cell tumors (7.5%), and the other tumors (22%) thymic pathologies, lymphangiomas, rhabdomyosarcomas, lipomas, hemangiomas, and Wilms' tumor. Complete resection of the tumor was performed in 86 patients, partial resection of the tumor was the intervention in 11 patients. In 23 patients, biopsy was undertaken. Because of the high incidence of asymptomatic or nonspecific presentation such as the upper airway disease, the presentation of a mediastinal mass in children may be challenging. Neurogenic tumors or lymphomas are indicating surgery, if possible complete resection, for both benign and malignant conditions. Although surgery is the mainstay of therapy for most mediastinal tumors, an experienced multidisciplinary approach is necessary.