OBJECTIVE: To explore a new surgical treatment of old atlantoaxial dislocation. METHODS: 5 patients aged 12 to 45 years, who suffered from old atlantoaxial dislocation for 1 to 4.5 years, received the new surgical treatment by the transoccipitocervical posterolateral approach, and expansion of the foramen magnum, odontectomy and bony fusion of the occipitoatlantoid region were performed. Neurological examinations and CT scan were undertaken after operation. RESULTS: All 5 patients survived. Sensory function recovered almost completely and motor function was better more than 1 degree. CT scan showed the diameter of the spinal canal restored well. CONCLUSION: The transoccipitocervical posterolateral approach is an ideal and safe pathway to reach the site of old atlantoaxial dislocation and the operating field is exposed completely. Anterior-posterior decompression and occipitocervical spinal fusion can be performed simultaneously