There have been several reports on surgical interventions in patients with adult cervical spondylotic myelopathy associated with athetoid cerebral palsy; however, the long-term effectiveness of these interventions has not been demonstrated. We have performed surgical treatments--posterior fusion with wave-shaped rods and anterior interbody fusion with internal fixators-- in 20 patients. The present study included 17 of these patients, 16 men and 1 woman, and their mean follow-up period was 8.6 years (range, 5-15.5 years). One year after surgery, walking ability was improved in 14 patients. Pain in the upper extremities and muscle weakness of the deltoid were alleviated in all patients. One patient showed recurrence of myelopathy after 8.5 years' follow-up. Our surgical technique is effective in patients with cervical spondylotic myelopathy secondary to athetoid cerebral palsy, even in those with severe involuntary movements. Postoperative rigid external fixations are not required.