Objective To investigate the pathological significance of an ubiquitin ligase hHrd1 involved in human breast carcinogensis. Methods By using immunohistochemical SP method, the expressions of hHrd1 protein were determined in normal human mammary epithelium, mammary hyperplasia, fibroadenoma and primary carcinoma of breast. Results Expression level of hHrdl protein was significantly higher in human breast carcinoma than that in normal human mammary epithelium, mammary hyperplasia and fibroadenoma of breast. There was also significant difference between ductal carcinoma in situ (or with early infiltration) and invasive ductal carcinoma (P<0.05), and the former was weaker. The expression level of hHrdl correlated positively with tumor size (P<0.05), but not with histologic grade and lymph node metastasis(P>0.05). Conclusion An ubiquitin ligase hHrdl may play a role in carcinogenesis in human breast.