Abstract:【Abstract】 Objective To investigate the expression of matrix metalloproteinase inhibitor (RECK), matrix metalloproteinase9 (MMP9) in triple negative breast cancer(TNBC) and adjacent tissues of TNBC and its relationship with the clinicopathology of TNBC.Methods Immunohistochemical tissue microarray technique was used to detect the expression of RECK and MMP9 in 72 cases of TNBC and 72 cases of adjacent tissues.Results The positive expression rates of RECK in TNBC and paracancerous tissues were 4306% and 8056% (P=0000). The expression of RECK in TNBC was correlated with clinical stage (P=0.009), histological grade (P=0. 010) and axillary lymph node metastasis(P=0. 000). The positive expression rates of MMP9 in TNBC and paracancerous tissues were 625% and 1528% (P=0000). The expression of MMP9 in TNBC was correlated with tumor size(P=0017), clinical stage (P=0001), histological grade (P=0001) and axillary lymph node metastasis (P=0034). Negative correlation between RECK and MMP-9 expression in TNBC(r=-0195,P<005).Conclusion The lack of expression of RECK and overexpression of MMP9 are important biological indicators in the invasion and metastasis of TNBC, which may be the target of TNBC treatment.