Background: p63 is a member of p53 family of transcription factors which have important function in tumorogenesis and oncogenesis. It is involved in cellular differentiation and exposed in nuclei of myoepithelial cells of normal breast. Aim: To study immunoexpresion of p63 in the benign, insitu, and invasive ductal carcinoma of breast. Material and Methods: The present study was conducted on 110 cases of formalin fixed paraffin embedded histological sections of surgically resected breast tissue specimens suspected to have neoplastic lesions and mastectomy specimens already diagnosed as carcinoma on cytology for a period of one year. Result: p63 is strongly expressed in all benign breast lesion in form of continuous peripheral rim around ductal epithelial cells, except atypical ductal hyperplasia in which moderate expression of p63 was noted in form of scattered as less continuous rim of myoepithelial cells similarly moderate to weak expression with focal gaps was described in ductal carcinoma of in situ and no expression was noted in infiltrative ductal carcinoma. Conclusion: p63 is a hallmark of very poorly differential cells or cells component with higher histological grade in breast carcinoma. Hence p63 can be used as an indicator of aggressiveness of breast carcinoma as a marker of choice in differentiating benign and malignant breast lesions.