Common polymorphism in DNA repair genes may alter protein function and an individual's capacity to repair damaged DNA; deficits in repair capacity may lead to genetic instability and carcinogenesis. In present work we investigated the association between XPD Lys751Gln polymorphism and breast cancer progression. The polymorphism was analysed in breast cancer patients (n = 92) in blood. Blood samples from age matched healthy women served as control (n = 110). XPD genotypes were measured by PCR-RFLP. The distribution of the genotypes of the Lys751Gln polymorphism in patients differed significantly (p < 0.05) from those predicted by the Hardy-Weinberg equilibrium. There were significant differences in the frequencies of alleles between the breast cancer subjects and controls (p < 0.05). The results support the hypothesis that the Lys751Gln polymorphism of XPD gene may be associated with the incidence of breast cancer.