First data on the distribution and population abundance of black-capped marmot Marmota camtschatica (Pallas, 1811) in the riverhead of Okunaika (Kirenga-Lena basin) in the territory of newly created specially protected natural area of «Lebedinye Ozera (Okunaiskiy)» Regional Reserve is cited. Proofs of many years of existence of stable population of black-capped marmot in the studied area was gained. 44 families belonging to the 11 colonies were counted at altitudes from 1 610 to 1 810 m a.s.l. The highest abundance of marmots was recorded on the western slopes of the Ungdar Ridge (327 individuals). Quantity of marmot in the watershed sites with the Baikal Ridge is significantly lower (75 individuals). Data on antropogenic influence on the population was gained.