Abstract: Objective: To observe the effect of different concentrations of omega-3 polyunsaturated fatty acids on cell viability, prostaglandin E2 (PGE2) production and lipid peroxidation in the human gastric cell line BGC-823. Methods: The survival rate of tumor cells was determined by MTT assay, and PGE2 level was established with competitive ELISA. Total superoxide dismutase (SOD) was examined with the xanthine oxidase test and malondialdehyde (MDA) was detected using thibabituric acid (TBA). Results: After treatment with 30μg/ml or 45μg/ml of eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA), the survival rate of tumor cells was markedly decreased (P<0.001). The concentration of PGE2 and total SOD in the treated cells was decreased (P<0.05), whereas MDA was increased (P<0.05). Conclusion: Omega-3 polyunsaturated fatty acids can inhibit the growth of cultured cells through a mechanism involving PGE2 metabolism and lipid peroxidation.