Background: Atherosclerosis is believed to be caused by oxidative stress. Endovascular therapy (EVT) is effective for claudication of patients with peripheral artery disease (PAD). However, its effect on oxidative stress in PAD patients is unknown. Here, the impact of EVT on oxidative stress in PAD patients is investigated. Methods and Results: Twenty-five PAD patients (Rutherford stage II or III) who underwent EVT were enrolled. The levels of diacron-reactive oxygen metabolite (d-ROM; an oxidative stress marker), ankle-brachial index (ABI), and maximum walking distance at baseline and at 3 months after EVT were measured. As compared with baseline values, the maximum walking distance and ABI improved significantly after EVT (109.9±104.2 vs. 313.7±271.8m, P<0.0001; 0.61±0.15 vs. 0.91±0.13m, P<0.0001, respectively). The improved exercise capacity and arterial flow induced a significant decrease in d-ROM levels (from 472.8±64.8 to 390.2±46.7U.CARR; P<0.0001). The decrease in d-ROM levels after EVT was more prominent in PAD patients with a high baseline d-ROM level. The increased ABI (r=0.524, P=0.0007) and maximum walking distance (r=–0.416, P=0.039) after EVT were significantly correlated with the decreased d-ROM levels. Conclusions: The improved exercise capacity and peripheral blood flow induced by EVT decreases oxidative stress in PAD patients.  (Circ J 2014; 78: 1445–1450)