The recent discovery of the BRCA-1 and BRCA-2 genes as contributing factors to hereditary breast cancer has significantly improved our understanding of familial breast cancer. Deleterious mutations in both BRCA-1 and BRCA-2 in an individual patient is exceedingly rare, with few case reports in the literature, particularly among non-Caucasian, non-Jewish families. We describe here two cases of deleterious mutations in both genes in a cohort of Korean women with early onset breast cancer.