Collecting the marine sponges from Phu Quoc island, Kien Giang province, the study on bioactivities were conducted. The ethanol extract of Neopetrosia sp. showed significantly cytotoxic activity on the cancer cell Hep G2 with the IC₅₀ value of 56,34 μg/mL, by SRB method. This result suggests for further study on chemical examination of Neopetrosia sponge. The assays on others cancer cells lines are tested.