Aim To study the antiviral effects of glycosaminoglycan from Scallop Skirt(SS-GAG)on herpes simplex virus typeⅠ(HSV-Ⅰ)in vitro.Methods The direct effect on virus,the influences of SS-GAG on virus reproduction and synthesis effect in virus infecting cells were investigated in vitro utilizing the herpes simplex virus typeⅠand taking vero cell as host cell by MTT colorimetry and observing cytopathic effect.The cytoxicity of SS-GAG was measured by MTT colorimetry.Results Compared with the virus control group,SS-GAG-treated group could protect the vero cells effectively and heighten the cell activity(P0.01).SS-GAG-treated group could lessen the cytopathic effect induced by HSV-Ⅰ and inhibit virus replication.These effects became stronger with the increase of concentrations of SS-GAG.But SS-GAG was not observed to have a direct inhibitory effect on the virus.The SS-GAG did not show cell toxicity on vero cells within the concentrations of 50~1600 mg·L-1.Conclusion SS-GAG showed siginificant activity of protecting host cells and anti-viral effect on HSV-Ⅰ in vitro.