We investigated the association between Arg399Gln polymorphism in DNA repair gene XRCC1 and chronic myeloproliferative diseases. 79 patients with chronic myeloid leukemia (CML), 91 patient with polycythemia vera (PV), 132 patients with essential thrombocythemia (ET). 50 patients with myelofibrosis and 114 controls were included in the study. We genotyped the polymorphism in XRCC1 gene by using polymerase chain reaction in real-time with TaqMan assay. The detection and quantification of the JAK2 gene V617F mutation allele burden was carried out by means of "Pyromark q24" pyrosequencing. The presence of at least one XRCC1 399Gln allele was found to be significantly different in patients with CML (OR 1.53; 95% CI 0.67-3.51) and ET (OR 1.31; 95% CI 0.61-2.78) in comparison with controls. The presence of XRCC1 399Gln allele was associated with the resistance to imatinib. We found no interactions between the XRCC1 genotype and the level JAK2 allelic burden. These data suggest about a significance of the XRCC1 gene product in the control of precursor cells of the myeloid differentiation in CML and ET cells. Testing Arg399Gln polymorphism in XRCC1 gene may be useful for the assessment of the prognosis and treatment efficacy.