Mouse monoclonal antibody was used for this study. This study was undertaken to define the prognostic value of the expression of Cathepsin-D in 121 breast cancer patients. The results were as follows: 1) Overall, 53,7% of patients were positive for Cathepsin-D 2) Positive staining did not correlate with age, estrogen receptor status, tumor size, axillary nodal status, tumor stage, menopausal status, pathologic grade, DNA ploidy and S-phase fraction.