We report on a biochemical study investigating some aspects of the systematics of the widespread glider genus Petaurus. P. breviceps is genetically quite distinct from both P. abidi and P. norfolcensis. Within P. breviceps there is evidence of marked population structuring. Among New Guinean populations of this species, those from Tifalmin and Karkar I. are divergent, possibly at the subspecies level. However, previously named morphological subspecies from New Guinea do not correspond to the clusters of populations identified by electrophoresis. Within Australia P. b. breviceps and P. b. longicaudatus can be distinguished electrophoretically. Our data also suggest that P. n. norfolcensis and P. n. gracilis are genetically distinct.