Ten million new cases of a cancer and more than 6,2 million death from diseases of this group are registered annually in the world. From 5 to 40% of malignant new growths of all anatomic localizations have a hereditary etiology, and this percent increases in connection with growth of the general incidence. The syndrome of hereditary breast cancer (breast cancer) and ovarian cancer (OC) makes a significant contribution to oncological morbidity: it accounts for 5-7% of all cases of breast cancer and more than 10-15% of OC. Mutations in the classical genes of family breast cancer / BRCA1 and BRCA2 occur in about 20-30% of pedigrees. Hereditary BC and OC are characterized by an autosomal dominant type of inheritance with high (incomplete) penetrance, early age of appearance and pronounced genotypic and phenotypic heterogeneity. Genetic testing is performed as a part of genetic counselling. The main inclusion criteria are multiple affected family members with breast/ ovarian cancer, breast cancer at young age (under 35–50 years), ovarian cancer at any age, male breast cancer, morphological features of breast cancer (triple-negative, medullar tumors), ethnicity (Jewish ancestry).