Abstract: Expression of c-erbB-2 proto-oncogene in 67 cases of bone tumors and 8 cases of normal bone tissue were investigated by immunohistochemistry(s-p method).Expression of c-erbB-2 product was present in 48%(13/27)giant cell tumors of bone and in 65%(13/20) osteosarcomas.20 cases of osteochondromas and 8 cases normal group gave negative results.These findings indicated that c-erbB-2 protoncogene product was correlated with cell biological behavior of bone tumor and showed significantly higher positive rate with increasing of malignity of bone tumor.Further studies demonstrated that giant cell tumor of bone with high histological grade, soft tissue involved and local recunnence showed a bias toward a increasing in expression of c-erbB-2 product.Patients with osteosarcoma over 5cm in size had a higher expression too.Patients with c-erbB-2 positive had a worse prognosis.