The authors studied the prevalence of mutations associated with resistance to the CCRS coreceptor antagonists maraviroc and vicriviroc in Russia. Most (93.6%) patients infected with HIV-1 genetic subtype A (IDU-A), predominant in the CIS countries, were found to have maraviroc resistance mutations. These mutations appear to reflect the natural genome polymorphism characteristic of the variant IDU-A. Maraviroc resistance mutations were of limited occurrence (2.8%) among the samples of virus subtype B in Russia. There were no vicriviroc resistance mutations in both the HIV-1 genetic variant IDU-A and the samples of virus subtype B. There is a need for further clinical studies evaluating the real impact of these mutations on the efficacy of maraviroc in patients infected with the HIV-1 genetic variant IDU-A.