Two thirds of the patients with peripheral arterial occlusive disease have to be treated conservatively, for only up to 30% can be revascularized by operative methods. Using the pharmacological differential treatment the grade of compensation and localization of the obliterative process has to be considered. Ignoring the usual basic therapy (elimination of heart failure and pathological bradycardia, systemic walking-exercise, anticoagulation etc.) intrafemoral long-term application of energetic phosphate (i.e. nucleotid-nucleosid-mixtures) leads to a positive result in nearly two thirds (n = 97 legs) with a degree of II to IV of Fontaine. Whereas the snakes' encyme Ancrod with the effect of defibrination was successful in almost 70% of the patients with arterial insufficiency (n = 45) including the degree II B (painless walking-distance under 100 meters). Energetic phosphates, applied to the arteria femoralis, are most successful in degree II with claudication intermittens. Ancrod should be used respectively for patients with pain during rest. These results are discussed with respect to compensation and localization of arterial occlusive disease, acute and chronic measurements of the hemodynamics by use of Doppler ultrasound and strain gauge plethysmography and with respect to variation of the concentration of the metabolic parameters lactate and pyruvate--the latter when defibrination was performed.