Three new gamasid mite species belonging to the genus Macronyssus Kolenati, 1858 (Acari: Macronyssidae), namely, Macronyssus sibiricus n. sp., Macronyssus stanyukovichi n. sp., and Macronyssus tigirecus n. sp., are described (females only; males, protonymphs, and larvae remain unknown). All species are known from Western Siberia and belong to the Siberian–Far Eastern bat ectoparasite fauna complex. The parasite hosts are the eastern water bat Myotis petax Hollister, 1912, and Hilgendorf's tube-nosed bat Murina hilgendorfi Peters, 1880 (Chiroptera: Vespertilionidae). An identification key for females of the genus Macronyssus Kolenati, 1858, in the boreal Palearctic region is presented.