Abstract: Objective To research the expression and relationship of matrixm etalloproteinase-2(MMP-2), metrixm etalloproteinase-9(MMP-9) and collagen IV in breast ductal carcinoma.Methods Immunohistochemistry double staining was used to detect the expression of MMP-2, MMP-9 and collagen IV in 60 cases of breast ductal carcinoma and analyze their correlation.The relations between MMP-2, MMP-9 and breast ductal carcinom a tumorsize, lymphnode metastasis, and C-erbB-2 were analyzed.Results The positive expression rate of MMP-2, MMP-9 in breast ductal carcinom a was 75% and 80%, respectively, which were significantly higher than the rate of 10% in normal breast tissues.MMP-2 and MMP-9 were expressed more strongly in the cancer cells approaching the basement membrane or breaking through the basement membrane.The positive expressions of MMP-2 and MM p-9 in the tumor diameter> 2cm, with lymphnode metastasis, and C-erbB-2 positive group were 83.9% and 90.3%, 87.0% and 91.3%, and 80.9% and 85.1%, which were significantly higher than 58.6% and 65.5%, 64.9% and 67.6%, and 46.2% and 53.8% of the correponding control groups.Collagen IV expression and the expression of MMP-2, MMP-9 was negatively correlated.Conclusion The degradation of collagen IV related to MMP-2 and MMP-9 may play an important role in local invasive and distantme tastasis of breast ductal carcinoma.The expressions of MMP-2, MMP-9 and collagen IV may have reference value in determining the invasive and metastatic potential of breast carcinoma and evaluating prognosis.