Stent fracture has emerged as a new problem in the percutaneous transluminal angioplasty of the superficial femoral artery (SFA). The aim of our study was to delineate the factors influencing nitinol stent fracture in the SFA. Forty consecutive patients with peripheral artery disease who underwent rescue stenting with a nitinol stent (Luminexx, Bard) in the SFA were enrolled between May 2004 and January 2005. Follow-up angiography was performed 13.6+/-1.0 months later to detect stent fracture. Stent fracture occurred in 11 patients (28%). Lesion length>100 mm, the number of stents used, the lesion involving the distal SFA, chronic total occlusion, and walking>5,000 steps per day were more frequently observed in those with stent fracture than in those without fracture. Of these variables, walking>5,000 steps per day was the strongest independent determinant associated with stent fracture by discriminant analysis (p=0.0027). Vigorous exercise adversely affects stent fracture in patients implanted with a nitinol stent in the SFA.