Abstract: Dipodids, aplodontids and sciurids recently collected from the Houldjin Formation in Erenhot, Nei Mongol, were described. All of them represent the first records of their kinds in Late Eocene of Nei Mongol. The discovery has not only expanded the distribution of these taxa inAsia, added new elements to the Houldiin fauna, but also provided new information in age determination of the Houldjin Formation. All the fossils described here were collected from IVPP Loc.1988001, east to the Railway Station of Erenhot.