OBJECTIVE To observe if the senile people with edentulous jaws had lower bone dentilies of mandible and coxofemoral region than those with dentate jaws, and to find the systemic risk factors which were responsible for the tooth loss and the formation of edentulous jaws. METHODS Two groups of senile people were selected. One group was edentulous and the other was dentate. All of them were examined by dual energy X-ray absorptiometry(DXA). RESULTS The senile people with edentulous jaws had significantly lower bone densities of mandible(P < 0.001) and they also had lower bone densities of coxofemoral region than the dentate group people. CONCLUSION It indicated that the decreased of bone densities of mandible and coxofemoral region was one of the systemic risk factors for tooth loss and the formation of edentulous jaws.