A representative mollusc fauna attributed to the late phase of the Karginian Interstadial (MIS 3) has been found in the Bol'shoj Naryn Palaeolithic site (Fore-Baikal region). The general organization of the strata at the Bol'shoj Naryn site has been established through excavations realized during the previous field seasons. It shows a modern soil made of sandy loess deposits 1 m thick, dated from the Sartan glacial stage, and underlined by a high viscosity paleosol layers which is up to 1 m thick developed during the Karginian Interstadial. The “cultural layer” has been correlated with the upper Karginian soil contains numerous stone tools and animal fossils. This paper focus on the mollusc assemblage attributed to the upper Karginian sediment.