Purpose: To assess calcium patterns in superficial femoral artery (SFA) disease before and after balloon angioplasty ± stent implantation using fluoroscopy, angiography, and intravascular ultrasound (IVUS) imaging and then correlate calcification severity and midterm clinical outcomes. Materials and Methods: A multicenter investigation was carried out to retrospectively review 130 symptomatic patients (mean age 73.2±8.4 years; 86 men) with de novo SFA lesions who had successfully undergone endovascular therapy (EVT) at 7 centers between January and October 2015. The primary outcome was lumen gain measured as minimum lumen area (MLA) in post-EVT IVUS images according to calcification severity. The secondary outcomes included rates of stent malapposition, restenosis, and clinically-driven target lesion revascularization (TLR). Results: A total of 102 (78.5%) cases had calcification in the lesions over a mean length of 64.3±72.8 mm. Of these, 70 cases were classified as having bilateral calcification according to fluoroscopy and angiography; 50 (49%) lesions had ≥180° calcification according to IVUS. The lumen gain in calcified lesions was significantly smaller than in the 28 noncalcified lesions (14.1±4.4 vs 17.8±5.2 mm2, p<0.001). IVUS-evaluated circumferential distribution of calcium (<180° or ≥180°) was independently associated with lumen gain after EVT (p<0.001). Among the calcification characteristics, a calcification angle ≥180° showed the strongest correlation to postprocedure MLA. Moreover, the restenosis rate was significantly higher in the severe (≥180°) calcification group (p<0.018). The severity of calcification was also associated with the risk of stent malapposition (p=0.022 for trend) but not TLR (p=0.57). Conclusion: IVUS evaluation of calcification in SFA lesions predicted lumen gain after EVT. Severe calcification in a ≥180° arc prevented successful dilation of the lesion with either plain balloon angioplasty or a nitinol stent. Accurate assessment of calcification patterns by IVUS is useful in maximizing the efficacy of endovascular therapy.