Introduction: Instead of vascular metallic stents with their permanent implant nature biodegradable stents can be applied. The aim of the study was to investigate the influence of Acetylsalicylic acid (ASA) versus ASA/Clopidogrel (CLOP) on acute/subacute thrombotic occlusion of a Poly-L-Lactid Acid (PLLA) stent after implantation in a porcine iliac model of stenosis. Materials and methods: A polytetrafluoroethylene (PTFE) aortobi-iliac graft (12/6 mm) was implanted in pigs (body weight bw: 37.4 ± 1.9) with creating of an iliac anastomotic stenosis. PLLA-stents (n=11) were placed across the distal anastomosis unilaterally (right: 6, left: 5) und balloon-dilated to 6 mm. Beginning 1 day before operation and continuing until the end of the study, the pigs received ASA 100mg orally alone (n=5) or in combination with CLOP 75mg orally (n=6). Intravenous heparin (50 IU/kg bw hourly) was administered as a continous infusion during the procedure. Doppler ultrasound (4MHz) was performed at the femoral arteries. After a follow-up aortoiliac CT-scan at 1 week, the segments containing the stents were surgically explanted and processed for histology (HE), and the animals were sacrified. Results: All PLLA-stents were sucessfully delivered at the distal anastomotic region and showed a complete stent-arterial wall contact after deployment on a macroscopically view. Stenting was successful in eliminating the anastomotic stenosis, proved by femoral doppler measurement, i.e. the poststenotic flow was abolished. One animal died 3 days after operation due to distortion of the right colon resulting in gangrene. At 1 week, all PLLA-stents using ASA alone (n=4) were shown to be occluded, whereas all PLLA-stents under the combination of ASA and CLOP (n=6) and all non-stented anastomotic sites (n=4) were patent. The residual lumen diameter was significant higher at the PLLA-stented (4.54 mm ± 0.16) than at the non-stented (1.89 mm ± 0.33) anastomotic site, p<0.001. The percent lumen stenosis of the PLLA-stented group amounted to 28.48% ± 2.98 compared to 61.01% ± 7.02 (p<0.001) of the the non-stented group, related to the inner diameter of the graft (6.35 mm ± 0.11 and 4.85 mm ± 0.03, respectively). The PLLA-stent associated neointimal restenosis was 5.07% ± 1.76, related to the normal lumen diameter (within the internal elastic lamina) of 4.78 mm ± 0.09. Conclusion: Acute/subacute occlusion of the PLLA-stent was prevented by a combination of ASA and CLOP. No significant stent-induced re-stenosis was observed. A longer follow-up period, however, is mandatory to evaluate chronic thrombosis/re-stenosis and the degradation behaviour.