In order to find potent virus-cell fusion inhibitory components from Korean edible clams, thirteen prepared polysaccharides were introduced to syncytia formation inhibition assay, which is based on the interaction between the HIV-1 envelope protein gp 120/41 and the cellular membutane protein CD4 of T lymphocytes. Among them, Meretrix petechialis showed a potent viruscell fusion inhibitory activity. Fusion index (F1) and percent (%) fusion inhibition of the polysaccharide of this clam were $0.21{pm}0.02$, and $67.52{pm}4.09$ at 100781m1, respectively. It exhibited almost equivalent virus-cell fusion inhibitory activity to that of dextran sulfate which was used as a standard control.