We have been developing a surgical navigation system for the graft replacement of thoracoabdominal aortic aneurysm. The system supports surgeons to detect the most important intercostal artery among the amount of cavities of the aorta. The world's first clinical trial was performed in July 2006 at Tokyo Women's Medical University. Up to now, the system has been utilized for nine clinical cases. For all cases, the system was assisted for surgeon's decision-making. Good clinical course without paraplegia. This system is highly effective for surgeons and patients to perform the safety and assure surgery.