Patients with aortic prostheses following aneurysm/dissection repair demonstrate an increased number of secondary aortic flow patterns. These may result in elevated forces acting on the vessel wall and thus preterm degenerative changes. Anatomically pre-shaped 90°-prostheses promise more physiological flow patterns and wall shear stress (WSS). The aim of this study was to compare WSS of patients with straight prostheses (n=8), 90°-prostheses (n=9) and healthy volunteers (n=12) based on 4D Flow MRI. Results revealed a tendency towards decreased WSS in regions distal to the 90°-prostheses, whereas in comparison to healthy volunteers, WSS values in patients with both prostheses were significantly increased.