Purpose: Stent-graft is widely used in the management of various aortic diseases. Most of all, surgical femoral artery cut-down was routinely used. However, we used truely percutaneous insertion technique for newly designed separating stent-graft in the treatment of thoracic aortic lesion. The purpose of this study is to describe technique, feasibility, and safety of our method. Materials and Methods: Four patients with thoracic aortic lesion were treated with percutaneous separating stent-graft. Arteriotomy was not needed in all four patients. Four patients had Stanford type B aortic dissection(n=1), and saccular aneurysm(n=3). The cause of saccular aneurysm was pulmonary tuberculosis in two, post-operative complication in one. The separating stent-graft consists of two stents; a graftstent and inner bare stent. The graftstent has three parts; proximal stent, Dacron graft, and distal stent. The proximal and distal stents were connected to the Dacron graft using Prolene suture. The gap between two stents and Dacron graft was 0.5cm. The introducing sheath for separating stent-graft was 12F. In order to place the separating stent-graft, we deployed the preloaded graftstent first, and then inner bare stent was deployed through the 12F sheath from the 10F cartridge. Results: Separating stent-grafts were successfully deployed without complications in all four patients. The diameter of the graft was 34mm, and the length was 8 to 10cm. There was no peri-graft leak immediate after stent-graft placement. At one-week follow-up, all devices were intact with complete exclusion of aortic dissection and saccular aneurysms. Two patients were died 34, 76 days after stent-graft placement because of sepsis and massive hemoptysis. In two patients, during follow-up period of 236, 239 days, no complication related to stent-graft was developed. Proximal perigraft leak was detected in the patient with aortic dissection at one-month follow-up CT scan. Conclusion: Percutaneous insertion of stent-graft seems to be an effective tool for thoracic aortic lesion. The newly designed separating stent-graft warrants further investigation in the noninvasive treatment of thoracic aortic lesions.