The fatigue behavior of Nitinol has recently gained a lot of attention driven by its application in harsh environments, such as in superficial femoral arteries (SFA) and in percutaneous heart valve replacement and repair. Unlike conventional materials, Nitinol possesses a number of unique fatigue properties which will briefly be summarized in this paper. Among those, rapid crack propagation in Nitinol is of particular importance. To date, the role of surface quality and microstructural imperfections – both assumed to strongly affect crack initiation – and their effect on the fatigue behaviour of Nitinol have not been well quantified. The authors investigate the role of both effects based on accelerated radial compression and rotation and bending fatigue tests performed on Nitinol stents.