Objective To investigate the differences in expressions of P-glycoprotein (P-gp), breast cancer drug resistance protein (BCRP) and pulmonary resistance protein (LRP) between primary breast carcinoma and metastatic lymph nodes. Methods The expressions of P-gp, BCRP and LRP in breast cancer tissues, including 126 primary carcinoma and 66 metastasis lymph nodes, were determined immunohistochemically on formalin-fixed, paraffin-embedded tumor sections. Results (1)The positive expression rates of P-gp, BCRP and LRP were 41.27%(52/126), 38.89%(49/126),and 65.87%(83/126) in primary breast carcinoma, and were 59.09% (39/66),63.64%(42/66),and 60.61%(40/66) in metastatic lymph nodes, respectively. The positive rates of P-gp and BCRP in the metastatic lymph nodes were significantly higher than those in primary cancer tissue(P<0.05); there was no significant difference in expression of LRP (P>0.05) .(2) There was a poor consistency in P-gp and BCRP expression between the primary and metastatic sites(P<0.01, Kappa value were 0.276 and 0.356); there was a consistency in LRP expression between the primary and metastatic sites(P>0.05).(3) The co-expression rate of two resistance proteins in primary breast carcinoma was 35.71%(45/126), of three resistance proteins was 15.08%(19/126), and of two or three resistance proteins was 50.79%(64/126), being significantly higher than that of a single protein 33.33% (42/126,P<0.05). The co-expression rate of two resistance proteins in metastasis lymph nodes was 53.03%(35/66), which was significantly higher than that of a single protein 27.27%(18/66,P<0.05). The co-expression rate of three resistance proteins was 16.67%(11/66), two or three resistance proteins was 69.70%(46/66), which was significantly higher than that of a single protein (P<0.01). Both the co-expression levels of two resistance proteins and two or three resistance proteins in metastatic lymph nodes were significantly higher than those in primary cancer (P<0.05) .(4)Kaplan-Meier analyses revealed that patients with P-gp, BCRP and LRP expressed in the metastatic lymph nodes had a lower 5-year survival rate compared with patients whose primary breast cancer being positive for them. Conclusion The expression of P-gp and BCRP is different between the primary and metastatic breast cancer sites, and there is no significant difference in LRP expression. Coordination of multi-protein expression is a major feature of resistance. Metastasis lymph nodes may have a stronger resistance.