The objective of this study was to determine the anticancer effects of the Pacific oyster (Crassostrea gigas) in vitro. For this study, the lipid extracts of C. gigas were prepared using several organic solvents: methanol, chloroform, hexane, methanol:chloroform=1:1, chloroform: hexane=1:1. The anticancer activity of the extracts was evaluated using cell cycle and apoptosis assays analyzed by a flow cytometry. Of all the extracts, the hexane extracts exhibited the highest anticancer activity compared to the other extracts. The hexane extracts were further separated and purified using thin layer chromatography. The final isolated lipid compounds were identified their components as palmitic acid, margaric acid, and stearic acid. These results indicate that this combination of lipids effectively inhibit in vitro human prostate tumor growth by inducing apoptosis of cancer cells.