Thoracic endovascular aneurysm repair for aortic arch aneurysm became more difficulty because of the curvature of the aortic arch and the presence of the supra-aortic vessels. If lesion has short proximal landing zone, the stent graft might cover the origin of important branch vessels on the aorta. Classic chimney technique have been proposed to solve this problem. But, this technique requires cutdown of carotid artery, more invasive procedure and is not suitable for cases of equivocal proximal landing zone. The authors describe two types of modified chimney techniques(MCT). Anterograde MCT : Left brachial artery is punctured and select left carotid artery by VTK, Simmons catheter(Fig.A). 035 inch Amplatz stiff wire put into left carotid artery through innominate artery in advance. And then aortic stent graft cover left carotid artery, stent graft or bare stent put into left carotid artery (Fig.A). Advantage of anterograde MCT is safety. But, it sometimes requires more procedure time. We successfully performed 2 cases of anterograde MCT for huge aortic arch aneurysms. 83 years old female, 76 years old male didn���t have complications during 11 months, 9 months respectively. Retrograde MCT : Aortic stent graft is deployed across left carotid artery and left subclavian artery through left femoral artery(Fig.B). Aortic stent graft is positioned at origin of left carotid artery covering two third of left carotid artery. And then, left carotid artery is selected via right femoral artery. stent graft or bare stent is deployed into left common carotid artery by retrograde MCT(Fig.B). Advantage of retrograde MCT is simple procedure. But, it may have difficulty to select left carotid artery after deployment of aortic stent graft covering two third of left carotid artery. We successfully performed 2 cases of retrograde MCT for 73 years old male with huge aortic arch aneurysm, 49 years old female with aortic arch disection.There were no complications during 28 months, 23 months respectively.