We studied occurrence of allele variants *1, *2, *3, and *17 of CYP2C19 gene and polymorphic variants of ABCB1 gene in clopidogrel treated patients from West Siberian and Far Eastern regions and determined contribution of these polymorphisms to laboratory efficacy of clopidogrel. In dependence on magnitude of change of platelet aggregation we distinguished groups of patients with different sensitivity to clopidogrel. We found association between polymorphic variant CYP2C19*2 with changes of platelet aggregation after administration of clopidogrel. An additional group of patients with augmented platelet aggregation after administration of clopidogrel was detected. There was no correlation between the latter effect and any of studied polymorphisms.