Objective: The aim of the study was to investigate inhibitory effects of breast-cancer metastasis suppressor 1 protein (BRMS1) on primary tumor growth and metastasis of human gastric cancer (GC) cells in nude mice. Methods: We compared the expression of BRMS1 in the primary gastric tumor and metastatic gastric tumor by immunohistochemistry. Expression of BRMS1 also was detected in the GC cells by RT-PCR and Western blot. Three groups of cultured human GC cell line SGC-7901, were maintained: transfected cells with pcDNA3.1(-)B/myc-BRMS1; negative control cells with pcDNA3.1/myc-his(-)B; and blank control cells without any transfection. Histologically intact samples of the cells, maintained by passage in the subcutis of nude mice, were transplanted orthotopically into stomach walls of nude mice to establish a nude mouse model of human gastric carcinoma. Their primary tumor growth and metastasis were then observed. Results: The expression of BRMS1 was markedly stronger in the primary gastric tumor compared with metastatic gastric tumor. We also detected BRMS1 gene and protein in the gastric cancer cell lines. Numbers of metastasis tumors significantly differed among mice infected with transfected cells, with negative controls and with blank controls (4.38 ± 0.60, 7.75 ± 0.59, and 7.63 ± 0.65, respectively; P < 0.05). However, there were no significant differences in the size of orthotopic tumors among mice infected with transfected, negative control and blank control cells [(12.02 ± 0.70), (12.71 ± 0.63) and (12.89 ± 0.71) mm, respectively; P > 0.05]. Conclusion: BRMS1 suppresses metastasis of GC cells, but does not inhibit growth of gastric tumors. Objective: The aim of The study was to investigate inhibitory effects of breast-cancer metastasis suppressor 1 protein (BRMS1) on primary tumor growth and metastasis of human gastric cancer (GC) cells in nude mice. Methods: We compared the expression of BRMS1 in the primary gastric tumor and metastatic gastric tumor by immunohistochemistry. Expression of BRMS1 also was detected in the GC cells by RT-PCR and Western blot. Three groups of cultured human GC cell line SGC-7901, were maintained: transfected cells with pcDNA3.1 (-) B / myc-BRMS1; negative control cells with pcDNA3.1 / myc-his (-) B; and blank control cells without any transfection. Histologically intact samples of the cells, maintained by passage in the subcutis of nude mice, were transplanted orthotopically into stomach walls of nude mice to establish a nude mouse model of human gastric carcinoma. Their primary tumor growth and metastasis were then observed. Results: The expression of BRMS1 was markedly stronger in the primary gast ric tumor compared with metastatic gastric tumor. We also detected BRMS1 gene and protein in the gastric cancer cell lines. Numbers of metastasis tumors significantly differed among mice infected with transfected cells, with negative controls and with blank controls (4.38 ± 0.60, 7.75 ± 0.59 , and 7.63 ± 0.65, respectively; P <0.05). However, there were no significant differences in the size of orthotopic tumors among mice infected with transfected, negative control and blank control cells [(12.02 ± 0.70), (12.71 ± 0.63) and (12.89 ± 0.71) mm, respectively; P> 0.05]. Conclusion: BRMS1 suppresses metastasis of GC cells, but does not inhibit growth of gastric tumors.