Postirradiation neuropathy of the brachial plexus is a chronic progressive disorder initially showing stepwise deterioration. Cardinal symptoms are sensory (dysaesthesia, paraesthesia, anaesthesia) and/or motor (paresis, paralysis) deficits and pain. Since such symptoms and signs may also be caused by tumour growth, pre-and intraoperative diagnosis must check neoplasia. Any treatment is only palliative. The aim is to slow down progression and to afford relief from pain as long as possible. Motor deficits are irreversible, except proximal muscle movements, especially in the elderly. Non operative treatment is the basis for therapy in every patient. Because of high rates of severe complications surgical revision of the brachial plexus without additional adjacent soft tissue defect is only rarely indicated. External neurolysis of the brachial plexus is more commonly performed, using a myocutaneous local or free flap, if the nerve structures have already been laid open in the region of the operation after removal of the tissue that had been damaged by irradiation.