To evaluate the influence of postoperative pharmacotherapy (antiplatelet therapy with acetylsalicylic acid (ASA) or oral anticoagulation) following various peripheral vascular surgical interventions (femoro-popliteal reconstruction, femoro-popliteotibial venous bypass;) two clinical series of patients were analysed (A1-2) and we made the hypothesis that adjuvant therapy may be beneficial. Thereafter two clinical trials were carried out (B1-2), to assess the value of postoperative antiaggregant and anticoagulant treatment. It was not possible to demonstrate any influence of ASA on improving patency at the iliaco-popliteal level or on patient survival. It was concluded that the ASA dosage of 1500 mg daily was too high, and produced severe side-effects, probably leading to insufficient patient compliance to therapy. In the B2 trial 130 patients received a femoro-popliteal above- or below-knee vein bypass, and were assigned to the therapy group (n = 66) and treated with anticoagulants or to the control group (n = 64) which received no therapy. During the follow-up, for a maximum of 10 years, the probability of bypass function, limb salvage and patient survival were significantly in favour of the treatment. The described single centre clinical trial B-2 produced in accordance with other trials a level II evidence in favour of postoperative pharmacotherapy. Level 1 trials assessing the direct comparison of antiaggregant versus anticoagulant therapy are underway, but results are unavailable yet, similarly the results of the Antithrombotic Trialist's Collaboration (ATT) are currently unknown.