The Somali lesser galago Galago gallarum is a little-known nocturnal, arboreal, primate of Ethiopia, Somalia and Kenya that lives in dryer habitats than any other primate in Africa. This paper presents an overview, based upon a detailed review of the literature and on our own preliminary observations, of what is known about the taxonomy, distribution, abundance, ecology, behaviour and conservation status of G. gallarum. We found G. gallarum to be relatively easy to identify and observe in the field, and to be sympatric with the northern lesser galago Galago senegalensis in Meru National Park. The phenotypic characters, habitats and loud (advertisement) call of G. gallarum are distinct, as are some of its behaviours.