Today, prevention of breast cancer (BC) is a great demand. The exact estimation of the individual BC-risk is a prerequisite for the participation on early cancer detection or the use of preventive medication or surgery. Various models for risk assessment of BC development or the presence of a predisposing mutation (i.e. BRCA1 or BRCA2) are used, but the statistical individual risk assessment still remains uncertain. Calculating an elevated risk or detection of a predisposing mutation leads to the recommendation of preventive measurements. After detailed assessment, prophylactic bilateral mastectomy is an option to consider for mutation carriers. For women with low BC-risk, chemoprevention can be discussed. Chemoprevention with tamoxifen (TAM)--indirectly supported by BC data from the raloxifen (RLX) prevention trial for osteoporosis and cardio-vascular disease--points to the right direction. Results from the three published TAM prevention trials are variable. Life time risk, age and life style have to be considered in the adapted individual risk-benefit assessment. The lack of long term risk data for chemoprevention and the effect on survival are arguments contra the routine use of TAM as a chemopreventive agent.