Subintimal percutaneous transluminal angioplasty (SIA) is a treatment option for long segment occlusions in the lower limb arteries. In the present study the factors influencing success and patency following SIA in patients with TransAtlantic Inter-Society Consensus (TASC) C and D peripheral arterial disease (PAD) were investigated. The 63 consecutive SIAs were performed in 54 consecutive patients suffering from limb ischemia with TASC C and D lesions. Follow-up consisted of routine office visits with pulse examination, ankle-brachial index (ABI), and serial surveillance by color duplex ultrasound and scanning at 3- to 6-month intervals for 1 year. The morphology of lesions in all patients were type C (n=13, 20.6%) or type D (n=50, 79.4%). SIA was technically successful in 59 of 63 arterial occlusive lesions (93.6%). Post-procedural ABI was 0.89+/-0.16. The mean increase in ABI after SIA was 0.45 (range, 015-0.87). The primary patency rate at 12 months was 51.7%. Occlusion length, lesions involving the distal superficial femoral artery (SFA), and post-procedural distal run-off vessels (P=0.04, 0.006, 0.018, respectively) were independent patency determinants by multivariate analysis. The length of the occlusion, lesions involving the distal SFA, and post-procedural distal run-off vessels were strong independent predictors for 1-year patency in TASC C/D severe occlusive femoropopliteal artery disease treated by SIA.