The rodent fauna of the locality Olalla 4A is composed of Theridomorpha, Cricetidae, Gliridae, and Sciuridae. A new genus of Cricetidae is described: Atavocricetodon, with three new species: Atavocricetodon atavoides sp. nov., A. nanoides sp. nov., and A. minusculus sp. nov. Two new species of Gliridae are described: Gliravus olallensis sp. nov. and Bransatoglis parvus sp. nov. Comparison with Montalban led to the description of yet another new species from that locality: A. hugueneyae. Discussion of the Olalla fauna shows that it must be younger than the 'Grande Coupure' and older than the classical locality of Montalbán, in other words Early Oligocene.