Abstract: Objective: To investigate the effect of the L-selectin, integrin α L and integrin β 2 expressions on the multi-ple-organ metastasis of breast cancer of TA 2 mice.Methods:The pathologic character of spontaneous breast cancer with multiple-organ metastasis (high metastasis, Group A) and without distant metastasis (low metastasis, Group B) were ob-served by macroscopy and H&E staining sections. The level of the L-selectin, integrin α L and integrin β 2 expressions in Group A, Group B and the metastatic tumors of Group A were detected using the immunohistochemical method. The level of the mRNA of L-selectin, integrin α L and integrin β 2 relative expressions in the prmary tumors of Group A and Group B were detected by Real-time PCR method. Results: Hemorrhage and necrosis were visibly seen in all the primary tumors of the Group A which were poorly differentiated or undifferentiated. Pulmonary, hepatic and splenic metastases, and angioge -netic mimicry were observed in these tumors. The average posi tive cel l percentage of integrin α L and L-selectin in primary tumors of Group A and Group B were 24.81% vs.10.47% and 39.81% vs.16.75%, respectively. The expressions of the pro-teins were significantly higher in Group A than in Group B (Z=- 2.31, - 2.14, respectively; P<0.05), while there was no signifi-cant di fference in the expression of integrin β 2 between the two groups. In Group A, the average levels of L-selectin expres -sion were 39.81%,39.07%,62.09% and 55.51% in the primary tumors, and the pulmonary, hepatic and splenic metastatic tumors, respectively, among which the average expression of L-selectin was significantly higher in liver metastatic tumor than in primary tumor (Z=- 2.24, P=0.025 ), whi le there was no markedly di fference in the expression of integrin α L and integ-rin β 2 between the primary and metastastic tumor. The levels of L-selectin and integrin α L mRNA relative expression were