In order to clarify the functional prognosis of accessory nerve injury after nerve repair and nonsurgical treatment, 27 of our cases with accessory nerve injury were studied. 20 cases were followed up for more than 8 months. In ten cases treated conservatively, the dull feeling and hypaesthesia did not improve. However, pain and dysfunction of the shoulder improved in half of these cases. In ten cases treated surgically, nerve suture was performed in two cases, nerve graft in five cases and neurolysis in three cases. In the surgically treated group, subjective complaints disappeared in all cases, but hypaesthesia or contracture of the shoulder persisted in three cases. Surgical treatment of the accessory nerve is recommended in fresh cases with complete paralysis and in cases in which there is no sign of nerve recovery within one year after the original injury.