The genus Hylopetes consists of 8 or 9 species of small flying squirrels. There has been much nomenclatural confusion over 3 of these species: H. platyurus (the gray-cheeked flying squirrel), H. spadiceus (the red-cheeked flying squirrel), and H. lepidus (the pink-cheeked flying squirrel). To address this taxonomic problem, we examined museum specimens and quantified pelage coloration, tail shape, and a number of craniodental characters. A discriminant analysis of craniodental variables discriminated among the 3 species and allocated all specimens correctly (P < 0.00001). We found that simple ratios of craniodental measurements coupled with pelage coloration characters can assist in the identification of these problematic species, although tail shape was not useful for discrimination. Based on our results as well as historical accounts and what is known about the biogeographical patterns of the region, we provide a description and discussion of the distributions for these species.