An analysis of 640 primary malignant bone tumors diagnosed and treated at the Center for Traumatology & Orthopaedics Hochiminh city during 13 years (1986 - 1998) show that: (1) Each type of bone tumors occurs at the special localization (s) and in the special ages, (2) There is the correlation between the incidence of tumor and the type of osteogenesis, the formation process of the skeletal system, (3) The greatest incidence of malignant bone tumors (64, 5%) is between the ages of 11 and 30, relating to the fasted growth period of the bone, (4) The most frequent tumors are osteogenic sarcomas (49, 2%).