BACKGROUND: Stent thrombosis and late restenosis are still major limitations in the clinical use of coronary stenting. Heparin-coated stent may reduce the incidences of stent thrombosis and restenosis. Heparin-coated stents were compared with control stents in a porcine coronary stent restenosis model in order to evaluate the effects of heparin-coated stent on stent restenosis. METHODS: Heparin was coated on a stent by deposition of an ultra-thin polymeric film containing amine groups by means of plasma polymerization. And then stent was immersed in heparin solution. Stent overdilation injury (stent:artery=1.3:1.0) was performed with bare (Group I, n=4) and heparin-coated (Group II, n=5) MAC stents in porcine coronary arteries. Follow-up quantitative coronary angiography (QCA) was performed at 4 weeks after stenting. The histopathologic assessments (KERN=*)of stented porcine coronary arteries were compared in between 2 groups. RESULTS: 1)Luminal area of stented artery was 7.05+/-1.25 mm2 in Group I and 7.67+/-2.85 mm2 in Group II, which were not different between two Groups. 2)Histopathologic stenosis of Group I was 35.7+/-13.2%, which was higher than 28.6+/-14.7% of Group II (p<0.05). Ratio of neointima/media was 1.16+/-0.52 in Group I and 0.87+/-0.31 in Group II and neointimal area was higher in Group I than in Group II (3.81+/-1.78 mm2 vs. 2.82+/-1.11 mm2, p<0.05 respectively). 3)PCNA (Proliferating cell nuclear antigen) index of GroupI was 10.0+/-2.2%, which was higher than in Group II (6.8+/-4.0%). CONCLUSIONS: Heparin-coated MAC stent may be effective in the inhibition of neointimal proliferation in a porcine stent restenosis model.