Background: Long-term outcome and the factors associated with restenosis after endovascular treatment (EVT) for iliac artery lesions in peripheral arterial disease (PAD) were evaluated. Methods and Results: EVT was performed for 487 lesions (TransAtlantic Inter-Society Consensus-II (TASC-II) Type-A: 275, B: 115, C: 37, and D: 60) in 436 PAD patients. The initial success rates for Type-B and Type-D lesions were lower than for Type-A lesions (P<0.05). The 3-, 5- and 10-year patency rates were 67%, 54% and 50%, respectively, with plain-old balloon angioplasty (POBA), and 88%, 82% and 75%, respectively, for stenting after suboptimal POBA, showing a significantly higher patency after treatment with a stent (P<0.001). With POBA, the long-term patency for Type-C/D lesions was lower than for Type-A/B lesions (P<0.05), but the patency after stenting did not differ significantly between Type-C/D and A/B. In the univariate analysis, the TASC-II classification, lesion length, pre- and post-procedural stenosis rates and stent use were found to be significant factors associated with restenosis (P<0.05). In the multivariate analysis, stent use (hazard ratio (HR) 0.345, confidence interval (CI) 0.193-0.616, P<0.001) and the post-procedural stenosis rate (HR 1.015, CI 1.001-1.030, P<0.05) were significantly associated with restenosis. Conclusions: Stent use and a low residual stenosis rate are significantly associated with patency, and favorable long-term patency can be obtained with stent placement for selected TASC-II Type-C/D lesions. (Circ J 2009; 73: 860 - 866)