Arterial endofibrosis is a recently discovered artery disease that is specific to endurance athletes. Cycling is the sport that has shown the greatest number of cases. The endofibrosis is located most frequently in the external iliac artery, but other locations must also be sought. Thigh pain during supramaximal exercise and patient questioning provide strong indications. The diagnosis is confirmed when there is concordance of exercise-induced symptoms, a positive exercise test result and discrete arteriographic characteristics. Treatment is based on folate supplements and standardised surgery carried out by an experienced surgical team.