In a consecutive series of 15 patients with unstable C1,2 cervical spine injuries treated with halo vest, 1992-1996, a total 7 patients (comprising 46%) among the patients with C1,2 cervical spine injuries, had odontoid fractures, no patient had neurologic injury. In all cases, initial treatment was Halter or skull traction for 1-2weeks. In the vitally stable state, they were stabilized with halo vest for 12-16 weeks. In 2 cases of C1,2 instability, initial treatment was internal fixation and halo vest for the same time. 2 cases of the patients, who were treated with halo vest, had additional posterior wiring and fusion due to instability checked after removal of halo vest. There was no other serious complications during the treatment. One case (25%) of 4 Anderson-d' Alonzo type II fractures was failed to unite. The halo vest was well tolerated in all patients and assured a high percentage of healing. Flexion-extension motion was measured with dynamic lateral cervical tomography. The age range was 17-67 (mean 41.3) years and male/female ratio was 3/2. Complications during the treatment were pin loosing (1 case) and halo vest frame breakage due to falling down. Pain on motion and stiffness of neck were the most frequently remained symptoms. But the symptoms were mild and did not usually have any major impact on return to work or leisure activities.