One, if not the only effective way of treating pain due to preganglionic avulsion of the brachial plexus is the Dorsal Root Entry Zone (DREZ) lesion procedure. In 1985 the author began to use ultrasound as a lesion-maker for operations in the DREZ. Since then, 127 (3 patients were operated on twice) DREZ-Operations have been carried out on 124 patients suffering from chronic pain due to brachial plexus avulsion. Different technical lesioning modalities were employed: ultrasonic discontinuous DREZ lesions in 20 cases and a new modality: ultrasonic DREZ-sulcomyelotomy in 107 cases. Analysis of the results after ultrasonic DREZ-operations revealed that ultrasonic DREZ-sulcomyelotomy was the most effective technical modality. Immediately after operation good pain relief was obtained in 103 (96%) out of the 107 patients operated on with the ultrasonic DREZ-sulcomyelotomy method, and in 15 (75%) out of the 20 patients with ultrasonic discontinuous DREZ-lesions. The total follow-up study (47.5 months on average) revealed 87% good results overall.