We performed resection of part of an injured peripheral nerve in 20 patients with post-traumatic neuralgia, after conservative treatment had failed. All had burning pain, paraesthesia and dysaesthesia in the area innervated by the injured nerve. We resected the nerve in the area in which the patient felt pain, and a further 3 cm proximal to the site of injury. In all cases, the local pain disappeared or markedly decreased. The areas of pain relief and of nerve resection coincided completely in 17 patients and partially in three. The results were assessed as excellent by five patients, good by 11, and fair by four. There were no poor results. Histological examination of the resected nerves showed Wallerian degeneration and immunohistochemical tests indicated that substance P, a polypeptide which may contribute to nociceptive transmission, was present in the tissue around the degenerated nerves