This study was aimed to investigate the effect of arsenic trioxide (As2O3) on expression of vascular endothelial growth factor-C (VEGF-C) and its receptor VEGFR-3 in gastric cancer in order to clarify the role of As2O3 in lymphangiogenesis and metastasis of tumor. The gastric cancer model was established in nude mice by using gastric cancer cell line SGC-7901. As2O3 was injected to the two treatment groups (2.5 mg/kg and 5 mg/kg) and the same volume of saline solution was injected to the control group. Expression of VEGF-C and VEGFR-3 were detected by immunohistochemistry and were analyzed with QWin550cW image Acquiring & Analysis System. The results showed that the expression of VEGF-C and VEGFR-3 in cancer cells significantly reduced in the arsenic -treated groups. The expression of VEGF-C and VEGFR-3 in 5 mg/kg group was significantly less than that in 2.5 mg/kg group. The gray ratio analysis confirmed that there were significant difference between control group and two treated group, as well as between 2.5 mg/kg-treated group and 5 mg/kg-treated group. It is concluded that As2O3 can inhibit expression of VEGF-C and VEGFR-3 of human gastric cancer xenografts in nude mice, which suggests that As2O3 may inhibit the lymphangiogenesis by suppressing the expression of VEGF-C and VEGFR-3.