The Bone and Soft Tissue Tumor Study Group (BSTTSG) of the Japan Clinical Oncology Group (JCOG) was established in 2002. At present, 26 institutions are participating as active members of the BSTTSG of the JCOG. In 2004, the first BSTTSG trial, JCOG 0304, was initiated. JCOG 0304 was a Phase II study of perioperative chemotherapy with doxorubicin and ifosfamide for patients with operable, high-grade, non-round cell soft tissue sarcomas (T2bN0M0) arising in the extremities. The results of JCOG 0304 suggested the efficacy of the perioperative chemotherapy on operable soft tissue sarcoma in the extremities and led to planning of the subsequent clinical trial for the disease. The BSTTSG has currently been conducting a Phase III trial, JCOG 0905, to investigate the superiority of the addition of ifosfamide to the standard chemotherapy with methotrexate, cisplatin and doxorubicin for operable, high-grade osteosarcoma. The BSTTSG is also conducting a JCOG ancillary study, JCOG 0905-A1, to evaluate the gene expression profiles of osteosarcoma treated in the JCOG 0905 study. The BSTTSG will further try to develop new standard therapy for bone and soft tissue tumors.