Objective : To evaluate the efficacy of fucoidan on the inhibition of neointima hyperplasia in a rabbit iliac artery in-stent restenosis model. Background : Neointimal hyperplasia, which was caused by smooth muscle cell proliferation, was noted to occur after performing percutaneous coronary intervention. Fucoidan inhibits smooth muscle cell proliferation by reducing mitogen-activated protein kinase activity. We studied the effects of fucoidan in a rabbit iliac artery in-stent restenosis model. Methods : Smooth muscle cells were treated with 12 µg, 120 µg concentrations of Fucoidan. The viability of smooth muscle cells was evaluated by XTT assay. Fucoidan coated stents (Fucoidan 5 mg/ml, 12.5 mg/ml) and bare metal stents were implanted in bilateral iliac artery of male New Zealand White rabbit. At 14 days and 28 days post-stenting, the iliac artery were harvested and stained with H & E. The neointima and media area were measured with a computerized image analysis program. Results : In vitro, Fucoidan treated (12µg) group showed inhibition of proliferation of smooth muscle cells compared with control. In vivo, Fucoidan coated group demonstrated suppression of neointima hyperplasia in a rabbit iliac artery in-stent restenosis model Conclusion : Fucoidan inhibits smooth muscle cells proliferation in vivo and neointima hyperplasia in rabbit iliac artery in-stent restenosis model.