Ewing sarcoma, together with neuroblastoma and central nervous system tumors, has got the lowest percentage of complete cure among all malignant diseases in children. From 1993 to 2003, 26 patients with Ewing sarcoma were treated in Pediatric Hematology and Oncology Department, Medical University in Lublin, Poland. In this study the character and time of the clinical symptoms to making the diagnosis, the abnormalities of laboratory tests, and the primary site of tumor were analyzed. The prognosis and results of treatment in children and adolescents were evaluated.