In order to search the association between, the histological response of high grade osteosarcoma to neoadjuvant chemotherapy and patient and tumor characteristics, amputation or en block resection specimens of 37 patients diagnosed as osteosarcoma in Ankara Oncology Hospital between 1997 to 2000 were studied. Two groups of patients having good or poor response to chemotherapy were determined according to the estimated tumor/necrosis ratios. There was a statistically significant association between the histological response to chemotherapy and the localization of the tumor (p<0.05). Poor response to chemotherapy was hig-her in the femur IocaIized tumors then the tibia and humerus localized ones. Poor response to chemotherapy was higher in the tumors diameter 10 cm or above than those tumors below 10 cm diameter.