AIM: To observe the anti-cancer effect of iNOS selective inhibitor (aminoguanidine, AG) and investigate the relationship between iNOS inhibitor and angiogenesis, infiltration or metastasis in MFC gastric cancer xenografts.METHODS: Fifty athymic mice xenograft models were established by inoculating gastric cancer cell MFC subcutaneously. Twenty-four hours later, 0.9% sodium chloride solution, mitomycin, low dosage AG, high dosage AG, mitomycin and AG were administered by intraperitoneal injection respectively. Thus these mice were divided into five groups of 10 each randomly: control group, MMC group,AGL group, AGH group, MMC+AGH group. Two weeks later the mice were killed, and the tumor weight, inhibitory rate were evaluated. Greiss assay was used to detect the nitric oxide levels in plasma. HE and immunohistochemistry staining were used to examine microvessel density (MVD)and the expression of iNOS, VEGF, and PCNA. Apoptosis was detected by using TUNEL assay.RESULTS: The inhibitory rates in MMC+AGH group and AGH group were 52.9% and 47.1% respectively, which is significant statistically compared with that of control group (0). In treatment groups, the cell proliferation index (PI)was lower and apoptosis index was higher than those of control group. Microvessel density, iNOS, and VEGF in MMC+ AGH group were 8.8±2.6, 2.4±1.1, and 2.1±1.4respectively, which is significant statistically compared with those of control group (68.3±10.6, 11.3±1.3, and 10.3±1.6). The NO level in plasma of MMC+ AGH and AGH group were 12.7±2.1 and 12.9±2.0 μmol/L. Compared with that of control group (46.6±2.3 μmol/L), the difference is statistically significant.CONCLUSION: AG has anticancer effect on gastric cancer,and it has positive synergistic effect with chemotherapeutic drugs. It may play important inhibitory roles in angiogenesis of gastric cancer. The anticancer effect of iNOS inhibitors may include inducing cell apoptosis, suppressing cell proliferation and reducing angiogenesis.