We examined 300 female patients with breast cancer and 300 healthy women for polymorphisms of the genes, belonging to: - the BER system XRCC1 gene - Arg399Gln polymorphism (rs25487), - the NER system XPD gene - Lys751Gln polymorphism (rs13181), - the MMR system hMSH2 gene - Gly322Asp (rs4987188), - the HR system XRCC2 gene Arg188His (rs3218536), RAD51 gene -4719A/T (rs2619679) and RAD51 gene -4601A/G (rs5030789). Here, MSH2 is linked to breast cancer.