[Objective] Quorum sensing inhibitory activity of some marine bacterial isolates was investigated to provide potential novel origins of natural products for the promising anti-bacterial therapeutic approaches targeting on the quorum sensing system of some pathogens. [Methods] In this study, we used Chromobacterium violaceum as the report-strain to screen for the quorum sensing inhibitory activity from some marine bacterial isolates by disc diffu-sion assay and double-layer soft agar assay. [Results] In total, 272 bacteria strains isolated from the sponge tissues collected around the San Juan Island had been tested. The results showed that 51 isolates exhibited the quorum sensing inhibitory activity. Among the active strains, bacterium No.74 had the strongest activity, which is deserved the further study on the isolation and identification of quorum sensing inhibitors. [Conclusion] Many marine bacterial isolates exhibit quorum sensing inhibitory, which indicated that marine bacteria are also a po-tential source for the natural quorum sensing inhibitors.