Background It is often hard to navigate a 9 French (F) balloon guiding catheter in patients with type III or bovine aortic arch. Also, a common carotid artery stenosis is challenging, because a guidewire cannot be advanced distally. We developed the combination of a 4F Simmons-type catheter and a 6F distal access catheter as a coaxial inner catheter to navigate a 9F balloon guiding catheter to overcome these difficulties. Materials and methods Medical record at our institution was retrospectively reviewed and carotid artery stenting cases in which the 4F Simmons-6F distal access catheter system was employed as a coaxial catheter to navigate a 9F balloon guiding catheter were identified. To construct this system, a 4F 145 cm SY3 (Hanako Medical, Saitama, Japan) and a 6F 118 cm Cerulean DD6 (Medikit Co. Ltd., Tokyo, Japan) were usually employed. A rotating hemostatic valve should be as short as possible and was attached to only a 9F balloon guiding catheter. The length of a 0.035-in. guidewire needed to be 180 cm or longer. Results During the study period, 106 carotid artery stenting cases were identified. Of these, this system was employed in 29 cases that included 5 cases with a steno-occlusive lesion at common carotid artery/external carotid artery, 10 with type III or bovine arch, and 11 harboring both. In all the cases, a 9F balloon guiding catheter was successfully navigated. Conclusion The 4F Simmons-6F distal access catheter system was useful in navigating a 9F balloon guiding catheter in patients with a common carotid artery stenosis, an external carotid artery occlusion, and an in-stent restenosis, especially when they also harbored type III or bovine aortic arch.