Part of breast and ovarian cancer cases develops on the hereditary predisposition, i.e. mutation in one of predisposing genes. Although this proportion is relatively small, 5–10%of all breast and ovarian carcinomas, it represents a group with clearly defined etiologic factor. Predictive analysis of unaffected family members allows to identify individuals at high risk of cancer and to include them into the programme of primary and secondary cancer prevention. Following article presents basic review of the hereditary predisposition to breast and ovarian cancer focusing especially on BRCA1 and BRCA2 genes, which are responsible for almost three-quarters of those hereditary tumours.

        Key words: breast cancer, ovarian cancer, BRCA1, BRCA2.