Breast cancer is the first cancer of women in the world and in Tunisia. Its incidence is in continuous rise.The risk factors of breast cancer are multiple. There are endogenous and exogenous hormonal factors, factors related to reproduction, demographic and breast factors, environmental factors and hereditary factors. Although the majority of cases are sporadic, it is estimated that 5-10% of cases have an inherited component. Two major susceptibility genes have been identified, BRCA1 (Breast CAncer 1) and BRCA2 (Breast CAncer 2), which play a key role in the DNA error repair process. Constitutional deleterious mutations in BRCA1 and BRCA2 are associated with a high risk of developing breast cancer, which reinforces the interest in identifying these mutations in families at risk.