Summary We assessed differences in the patterns of expression of matrix metalloproteases and their inhibitors (tissue inhibitors of metalloproteases) in ductal carcinoma in situ alone and admixed with invasive ductal carcinomas (n = 40), as well as in pure invasive ductal carcinomas (n = 40), immunohistochemically and using tissue arrays. The invasive ductal carcinoma components showed higher expression of matrix metalloprotease–9 and –13 than did the admixed ductal carcinoma in situ, whereas stromal fibroblasts of the invasive components showed higher expression of matrix metalloprotease–2, –7, –9, –13, and –14 and tissue inhibitor of metalloprotease–1 and –3 than did fibroblasts around the neoplastic ducts of the admixed ductal carcinoma in situ. Expression of matrix metalloprotease–14 and tissue inhibitor of metalloprotease–3 was significantly higher in the mononuclear inflammatory cells of the invasive components. By contrast, matrix metalloprotease–1 expression was significantly higher in stromal cells of the ductal carcinoma in situ admixed with invasive ductal carcinoma. The pure invasive ductal carcinomas had significantly higher expression of matrix metalloprotease–1, –9, –11, and –14 and tissue inhibitor of metalloprotease–1 and –3 than the invasive ductal carcinomas admixed with ductal carcinoma in situ. Our findings indicate a significant association of matrix metalloprotease expression by the periductal stromal cells of the ductal carcinoma in situ component of mixed tumors and the occurrence of distant metastasis. Our data suggest that the molecular matrix metalloprotease/tissue inhibitor of metalloprotease profile can contribute to better characterization of early breast carcinomas.