We report a case of atlantoaxial dislocation associated with von Recklinghausen's disease which developed after anterior cervical spinal fusion.Anterior spinal fusion was performed from C3 to C7 to prevent the progression of marked kyphosis (125 degrees) found in a 22-year-old man with von Recklinghausen's disease. Spondylosis was well established, and no further increase in kyphosis was seen. However three years after the operation, he complained of lower extremity tingling and had a spastic gait. Radiological instability of C1-C2 was then confirmed.The earlier anterior cervical spinal fusion was considered to be potentially involved in the pathogenesis of this patient's atlantoaxial dislocation.