Types of mtDNA with +16274EcoRV, which had been previously found in East Slavonic residents of Magadan, were identified on the basis of published data on nucleotide sequences of the hypervariable segment I (HVSI) of the mtDNA control region. These mtDNA types occurred in Slavs at a frequency of 7-14% and were assigned to four mitotype groups (1, 2A, 3B, and 5) restricted to Caucasoid populations. Regarding the evolution of mtDNA, this fact indicates that the C-T transition at position 16,278 arose independently in various groups of mtDNA types in Caucasoids. A new subgroup was isolated in Caucasoid group 5. One of the key mutations in this subgroup was variant +16398HaeIII (transition A-G at position 16,399), which was earlier detected in Russian populations at a relatively high frequency.