Abstract: Objective: To investigate the inhibitory effects of sulfated polysaccharides from Laminaria japonica on rat vascular smooth muscle cells (VSMCs) induced by basic fibroblast growth factor (bFGF). Methods: Rat VSMCs were obtained from the aorta of adult Sprague Dawley rats by attached explant method and identified by immunohistochemistry assay. VSMCs proliferation was induced by basic fibroblast growth factor (bFGF). The inhibitory effects of crude sulfated polysaccharide and its fractions on VSMCs proliferation were evaluated by MTT assay. Superoxide anion-scavenging activities of sulfated polysaccharides were investigated by xanthine /xanthine oxidase method. Results: At the concentration of 0.1-1 mg/mL, all sulfated polysaccharides dose-dependently inhibited bFGF-induced VSMCs proliferation except WPS-2. Similarly, all sulfated polysaccharides showed good superoxide radical scavenging capabilities except WPS-2. Conclusion: All sulfated polysaccharides can dramatically inhibit the proliferation of VSMCs induced by bFGF except WPS-2. The functional mechanism may be related to their antioxidant activities.