This 75-year-old male who fell from a 1-m hight road shoulder subsequently suffered persistent neck pain. On admission to our institute he exhibited no neurological abnormalities. CT scan revealed an odontoid Anderson type III fracture. We selected conservative treatment with external fixation using a hard collar. No cervical deformity was recognized over the course of a month and he was transferred to another hospital for rehabilitation. As a cervical X-ray performed a month later disclosed a progressive kyphotic deformity, he was readmitted to our institute for surgery. He underwent internal fixation with a Ransford loop between the occipital bone and the C3 lamina. During the operation we noted that his bone was very fragile. His postoperative course was uneventful and he exhibited no neurological deficits; his cervical alignmen stabilized completely. At his 2nd admission, his bone mineral density was 0.767 g/cm2, 64% of the young adult mean and thus indicative of severe osteoporosis. We conclude that careful observation and appropriate internal fixation are necessary in osteoporotic patients who manifest deformity following an odontoid fracture.