Wrist arthrodesis has been used successfully for the management of severe wrist flexion deformity when soft tissue procedures would not provide adequate correction. However, in athetoid type cerebral palsy which has a component of involuntary movement, the outcome of wrist arthrodesis has not been discussed much. We present our experience in 2 athetoid type cerebral palsy patients who underwent wrist arthrodesis due to severe involuntary movement of the wrist. One patient had a nonunion and both patients had unexpected aggravation of involuntary movement in the adjacent joints. Secure fixation using a pre-contoured plate is necessary and preparation for iliac bone grafting should be considered as proximal row carpectomy is usually not necessary in these patients. In addition, although single-event, multi-level surgery is advocated for patients with cerebral palsy, potential additional procedures for the adjacent joints should be discussed preoperatively because unexpected aggravation of involuntary movement of adjacent joints can occur after stabilization of the wrist.