Objective-To describe a surgical technique for, and report outcome after, extensive nasal septum resection in horses with congenital or acquired septal diseases. Study Design- Retrospective Study. Animals-Horses (5) with nasal septal deformity. Methods-Under general anesthesia, obstetrical wires were preplaced around the ventral, caudal, and dorsal aspects of the nasal septum by combinations of manual guidance (ventral and caudal wires) and use of a trephine hole on the dorsal mid-line (dorsal and caudal wires). The rostral part of the septum was incised with a scalpel and the ventral, dorsal, and caudal septal incisions were made with the preplaced wires. After septum removal, the nasal cavity packed with a tampon and a temporary tracheotomy was performed. Results-The diseased nasal Septum was completely removed in all horses. It was possible to direct the caudal cut at a sufficient angle so that the remaining stump was in a wide part of the nasal passage, where it would have minimal effect on airflow. Four horses healed, and returned to intended use but continued to make a slight respiratory noise during exercise. At 13 months after surgery, I horse with a concurrent wry nose was retired from race training after 2 additional surgeries failed to relieve exercise intolerance at high speed. Conclusions-The 3 wire-cut method of nasal septum resection was technically easy to perform and safe, allowed return to function in most horses, and produced ail excellent cosmetic appearance. C linical Relevance-This technique for nasal septum resection allows removal of a large portion of the nasal septum and provides a safe alternative to conventional techniques of nasal septum resection in the horse. (c) Copyright 2005 by The American College of Veterinary Surgeons.