One hundred and forty-five children with tumors, who applied to our clinic for radiation therapy between December 1992 and August 2001 were reviewed in this study. In this review, distribution of disease groups, sex, age and regional distribution were evaluated. The median age was 11 years (0-18). In 139 children with malignant tumors male/female ratio was 1.24/1. Central nervous system (CNS) tumors were seen the most frequently (30.2%), leukemia was the second (17.3%), and lymphoma was the third (15.1%) in frequency. CNS tumors were the more frequently in comparison with other most clinics in our series. On contrary to our series, leukemia was the most common in other series. We consider that it may be resulted from both CNS tumors may be the more being referred tumors than leukemia to radiation oncology clinics and patients with leukemia might be treated in other clinics, because there was no pediatric oncology in our hospital in some period.