Breast cancer is the commonest cancer among women and the second highest cause of cancer death. it remains a significant health problem and represents a significant worry for many women and their physician. During the fast years, intensive research has been focused on accurate risk estimation for breast cancer development. The aim of these efforts is to identify the "high-risk" group of women for breast cancer development. Preventive strategies (including intensive surveillance, chemoprevention, or prophylactic mastectomy) may be applied for the women at high risk for breast cancer development. Given the many management options, it seems reasonable that management of the high-risk woman be tailored to the level of risk she is willing to accept. In estimating the risk for breast cancer development, several factors should be taken into account (including age, reproductive factors, such as age at menarche and age at menopause or pregnancy and age at first live birth, history of benign breast lesions or breast cancer in situ [LCIS/DCIS], prior history of breast cancer, history of familiar or hereditary breast cancer, and environmental and lifestyle factors). Recently, quantitative risk estimation is possible by combining multiple risk factors into a comprehensible risk expression; this is of significant clinical importance, since it will reduce the considerable variation in management among health care providers. The Gail and the Claus model are the most widely used models for quantitative risk estimation. However, the clinician should understand that all models have some limitations that should be recalled as they are applied. It should be emphasized that risk assessment is a serious undertaking and should only be performed by those who have in-depth knowledge about risk factors, family pedigree analysis, comparative statistics, genetics susceptibility testing and the science of probability. (C) 2002 Elsevier Science Ltd. All rights reserved.