Data on distribution and biology of the Hilgendorf’s tube-nosed bat(M. hilgendorfi) in the Baikal region (Irkutsk Region and Republic of Buryatia) during 2002–2016 are presented in the article (n = 102). About 80 % of the bats were netted in August-September near entrances to large karst caves, and only 4 % – were found during wintering in the caves, the others were collected` in feeding habitats or in summer day shelters. Relative plenty of M. hilgendorfi in the lake Baikal region during the “warm” period of year – 6,3 %, occurrence – 22 %. Higher relative plenty and occurrence, in comparison with earlier published data on same region, the Far East and Western Siberia, are apparently explained by productive catching in the period of an autumn swarming at caves entrances. The ratio of males to females composed 3:1 during this period, the adult individuals dominated (more 90 %). Females prevailed when catching in feeding habitats, and the share of subadult bats composed about 50 %. New findings in Barguzin Reserve, Tunkinsky valley and on the Upper Dzhilinda Lake expand a know lage on M. hilgendorfi geography in the Baikal region. Body condition index of Hilgendorf’s tube-nosed bats in the period of migratory activity at caves in the south of Irkutsk region was much higher, than in the north of Buryatia.