Harasib 3a, a karstic deposit in the Otavi Mountains, Namibia, is of Late Miocene age (ca. 10 Ma) and has yielded many thousands of rodent cheek teeth. This paper deals with 1 493 cheek teeth belonging to the muroid family Gerbillidae of which three subfamilies are present at this site, one being new to science. Myocricetodontinae (808 teeth) are known by a new genus and two new species. Petromyscinae (680 teeth) are represented by a new genus and species, while the new subfamily is known by a minute new genus and species of which only 5 teeth are preserved at the site. Despite the fact that all the Harasib Gerbillidae are new to science, the material shows affinities with gerbillids from other parts of Africa, especially myocricetodontids. The petromyscines and the new subfamibly are the oldest known members of their respective lineages.