The aim of our study was to increase of survival of children with osteosarcoma by intensification of chemotherapy by inclusion of high dose methotrexate. 53 patients were treated in our centre between 2003 and 2007. Age are ranged from 5 to 16 years. 23 (43,4%) patients had metastetic disease. Polychemotherapy consist of alternating courses of CDDP, adriamicin, ifosfamide and etoposide and high-dose methotrexate (8–12 g/m²). In 25 (51%) cases have been received objective response (CR+PR). 38 (71,7%) patients alive at present time. 2 patients died from complications of treatment. 7 patients had PD, 1 — local relapse, 4 — metastatic relapse, 1 — combined relapse. 2-year OAS was 75,2±6,8%, 2-year RFS was 65±7,8%.