Breast cancer is the most common malignancy among women in the Western society. Over the past decades it has become apparent that breast cancer incidence rates are increasing steadily, whereas the mortality rates for breast cancer have remained relatively constant. Information through the media on this rising number of cases has increased breast health awareness but has also introduced anxiety in the female population. This combination of factors has made the need for prevention of breast cancer an urgent matter. Breast cancer does not seem to be a single disease entity. A specific etiologic factor may therefore have more influence on one form of breast cancer than another. So far though, as shown in our summary of current knowledge on established and dubious risk factors, no risk factors have been identified that can explain a major part of the incidence. Efforts to identify other ways for primary prevention have also been discouraging, even though breast cancer is one of the most investigated tumours world-wide. Thus, at this point in time, the most important strategy to reduce breast cancer mortality is early detection through individual counselling and organised breast screening programs. The recent isolation of breast cancer susceptibility genes may introduce new ways to reduce the risk of breast cancer in a small subset of women.