In the light of these evidences and because of the potential roles of estrogens in the early stages of human breast carcinogenesis, in the present study, we aimed to assess the promoter methylation status of both BRCA1 and 17βHSD-1 genes in the tumor and adjacent normal tissue from sporadic breast cancer patients to establish the role of epigenetic in regulating intratissue estrogen activity and thereby in the etiology of breast cancer. The gene discussed is BRCA1; the disease is breast cancer.