The screening of 453 high risk breast cancer patients from different regions of Chile revealed the presence of nine founder mutations, 4 in BRCA1 and 5 in BRCA2. These mutations are shared by 2 to 10 unrelated families spread in different regions of Chile, and correspond to 77.5% (55/71) of mutation carriers. The gene discussed is BRCA1; the disease is breast carcinoma.