Introduction: miRNAs are very important regulators in biological processes such as development, cellular differentiation, and carcinogenesis. Given the important role of miRNAs in tumorigenesis and development, it is worth investigating whether some miRNAs play roles in the anticancer mechanism of flavonoids. However, such a role has not yet been reported. We previously selected the promising anticancer agent 3,6-dihydroxyflavone (3,6-DHF) in pharmacodynamic experiments, which may serve as a leading compound for developing more potent anticancer drugs or chemopreventive supplements. The present study aims to investigate the chemopreventive activities of 3,6-DHF against mammary carcinogenesis.