Objective To investigate the possibility of using extendible distal femoral replacements in the treatment of osteosarcoma in growing individuals. Methods From December 1999 to March 2003, 3 cases (2 were typeⅡB, 1 was type ⅡA) with osteosarcoma were treated byextendible distal femoral replacements. Of the 3 cases, 2 underwent prosthesis extention operation, 1 was not operated. Results After the removal of tumor, the extremities of 2 patients were shortened by 4 to 5 cm within 2 to 3 years. After the lengthening procedure, the affected extremities were of equal length to the unaffected extremities and no drag symptoms of blood vessel and nerves were observed. Follow-up was done for 2 months to 3 years. There was no aseptic loosening. The function of joints was fairly good. Conclusion Extendible distal femoral replacements is an easy, convenient, and effective way to treat osteosarcoma.