Objective To explore the in vivo anticancer effects of luteolin with BGC-823 gastric carcinoma xenografts in nude mice and elucidate its mechanism. Methods After modeling of gastric carcinoma xenografts in nude mice, 40 BALB/c (nu/nu) nude mice were randomly divided into 5 groups(n=8 each). And an intraperitoneal injection of luteolin was administered at 10 mg/kg (low-dose), 20 mg/kg (middle-dose) and 40 mg/kg (high-dose) groups. And 5-fluorouracil (30 mg/kg) and control groups were also established. The growth curves of xenografts in nude mice were drawn and weight inhibition rates measured. The morphological features were detected by hematoxylin and eosin staining. And the protein expression levels of vascular endothelial growth factor A(VEGF-A) and matrix metalloproteinase 9 (MMP-9) were measured by immunohistochemistry. Results In vivo tumor formation test showed that tumor volume in nude mice treated with luteolin was smaller than that of control group. Tumor weights of high-dose luteoin group were lighter than those of the control ((0.290.01) vs (0.380.03) g). And the difference was statistically significant (P < 0.01). The rate of tumor inhibition in high-dose luteoin group was up to 24.87%. Lymphocytic invasion of tumor tissue was observed under light microscope in the treatment groups. Results of immunohistochemistry showed the positive cell integral of VEGF in middle and high-dose luteoin groups were 1.250.17 and 1.000.07 respectively. Both were significantly lower than that of control group (1.500.15, both P < 0.05). The positive cell integral of MMP-9 in high-dose luteoin group was markedly lower than that of control group (3.751.43 vs 9.001.08, P < 0.01). Conclusions Luteolin can effectively inhibit the in vivo growth of gastric tumor. The mechanism may be correlated with the stimulation of immune response and the down-regulated expressions of VEGF-A and MMP-9.