Karyotypes have been obtained for ten species of New Guinean dasyurid marsupials. All species have 2n = 14 chromosomes which, except for variation in size and shape of the X chromosome, are similar in morphology, not only between species but also to Australian species. The Y chromosome of all species is punctiform. C- and G-banding procedures have been applied to eight of the species and show (1) there are no major differences between species in amounts of C-band heterochromatin, and (2) the G-band patterns of the autosomes were virtually identical. These findings suggest that there have been no major karyotypic changes accompanying speciation of dasyurids in New Guinea. Since the G-banded karyotypes are also virtually identical to those reported for Australian dasyurids it would appear that this 2n = 14 karyotype probably represents the ancestral dasyurid form which can be derived as a result of a few inversions from an ancestral marsupial karyotype. These changes must have occurred very early in the dasyurid radiation as the) are found in all extant species and genera examined. However, virtually identical G-banded karyotypes may mask major differences in nuclear DNA values.