In patients with atherosclerosis lesions, hypoxia induces changes in the vascular endothelium which becomes procoagulant and proadhesive. The aim of this study was to investigate the influence of exercise on endothelium function and to relate plasma markers of endothelium with clinical status of patients with chronic obliterative arterial disease (COAD) of the lower limbs.Patients and Methods: 20 patients with a stage II COAD of the lower limbs, underwent a walking test on a treadmill with continuous measurement of the transcutaneous oxygen pressure (TcPO2) on the dorsum of the foot. Three plasma endothelium markers namely, thrombomodulin (TM), von Willebrand factor (vWf) and plasminogen activator inhibitor (PAI-1) along with leukocyte and platelet counts, prothrombin fragments 1 + 2 (F1 + 2) and the D-dimers were measured before exercise, at the onset of pain, on cessation of the test and during the recovery phase (1st and 2nd hours).Results: The platelet and leukocyte counts increased with exercise (p < 0.008 and p < 0.007) and returned to their original levels at the 2nd hour. There were no variation in the F1 + 2, D-dimers and vWf levels. The PAI-1 level fell at the 2nd hour (p < 0.006). The TM levels were inversely related to the TcPO2 levels at the different stages of the test. The angle of fall of the oxymetry (indicator of the speed of ischaemia) correlated with the changes in the TM on exercise (p < 0.05).Conclusions: Apart the transitory rise in the platelet and leukocyte counts on exercise, in exercise-induced ischaemia there was clear evidence of harmful effects on the endothelium of which the main indicator was the rise in the TM plasma level. On the basis of these clinico-biological findings, the justification for pushing walking tests in arteriopaths to the limit of pain, is questioned.