A representative mammal fauna attributable to the Karginian Interstadial (MIS 3, 36 000–23 000 BP) has been found for the first time in the Fore-Baikalian region. The faunal remains were recovered from Gerasimov’s and Bol’shoi Naryn Paleolithic sites in 2003–2008. Zooarchaeological investigations revealed 51 mammal species in the region, dominated by horse Equus sp., steppe lemming Lagurus lagurus, narrow-sculled vole Microtus gregalis and North-Siberian vole M. cf. hyperboreus. The early humans appear to have inhabited a forest-steppe, with local patches of tundra-like landscapes. The Karginian climate was warmer and more humid than during the subsequent Sartan glacial epoch (MIS 2).