External iliac artery endofibrosis is characterized by intimal fibrosis and often presents as a gradual decrease of exercise capacity due to exertional claudication-like symptoms, traditionally of the lower extremities.1 The data on the prevalence of iliac artery endofibrosis is limited to case reports; most describe endurance cyclists as the presenting patient.2–4 However, there also have been a few cases reported with high performance athletes, including triathletes and long-distance runners.5,6 The etiology of this condition is thought to be secondary to mechanical kinking of the external iliac artery during repetitive deep flexion movements, which is seen in certain endurance sports such as cycling or long distance-running.7 This is a case of a 43-year-old previous cyclist, now ultramarathon runner, who presented to clinic with severe and progressive exertional lower extremity pain.