Breast cancer is one of the main public health problems, approximately 10% are genetic. In a previous study carried out by our group, founder mutations in BRCA1 and BRCA2 genes were detected; this will allow early testing and detection of patients with high breast and ovarian cancer susceptibility in Colombia, and to implement prophylactic strategies. The aim of this study was to estimate the genetic component of breast cancer in Colombia, testing for the frequency and penetrance of germinal mutations in BRCA1 and BRCA2. 766 patients fulfilling the criteria of breast cancer diagnosis after 2004 were studied for founder mutations. The results were reported to the patients; frequency and penetrance were tested. Total frequency for founder mutations in BRCA1 and BRCA2 was 4.2% (CI 95%: 2.9-5.8), and penetrance at 50 years was 33, 3(CI 95%: 15.2 - 63.1) for BRCA1 and 32(CI 95%:11.8 - 70.9) for BRCA2. The high frequency of the mutations supports the need to implement genetic testing policy for patients with breast cancer independently of family history or age. It is necessary to continue the study to perform penetrance testing at the 70 year limit.