Over the past years there have been significant advances in breast cancer treatment and early detection. For the first time, a decrease in cancer mortality has been observed. Recently, much progress has been made in the understanding of carcinogenesis partly due to available new technologies to detect early molecular changes in the tissue. The knowledge of breast cancer carcinogenesis has provided possible opportunities to prevent breast cancer. Currently, several clinical breast cancer prevention trials are ongoing. This paper reviews issues related to breast cancer chemoprevention including identification of high risk cohorts, endpoint biomarkers, current and new chemopreventive agents as well as models to evaluate these agents.