The geographic variation of skull size and shape among populations of flying squirrels of the genus Idiurus was analyzed with multivariate techniques using up to 57 craniometric characters. The variability of body size and fur coloration was also studied. The results support the present division of the genus into two species, Idiurus macrotis and I. zenkeri. Further division, into subspecies, does not seem to be warranted at present, although distinguishable geographical populations exist in West, Central, and East Africa.