The aim of this study was to investigate the haemostatic effects of iloprost, a stable analogue of prostacyclin, in patients with peripheral arterial disease. In a group of 13 patients with obliterative arteriopathies of the lower limbs the plasma levels of thrombomodulin (TM), betathromboglobulin (beta-TG), D-dimer (DD) and plasminogen activator-inhibitor (pAI-1) were measured, and compared to the values obtained from 10 healthy volunteers. All the parameters were found to be significantly higher in vasculopathic patients. These haemostatic evaluations were carried out after 4 weeks of treatment with iloprost up to 2 ng/kg/min, 6 hours infusion per day. During and at the end of treatment a clinical improvement was recorded. The patients also showed a significant decrease in plasma beta-TG and DD at the end of treatment. These data suggest that iloprost exerts clinical improvement, in who may have a part the decrease of platelet activation and of fibrin turnover.