The helminth parasites of Macropus fuliginosus and Macropus giganteus are reported based on examination of a total of 285 animals extending, for the first time, across the entire geographical range of both species and including, where possible, data from previous regional studies. A total of 64 species of helminths was found including 42 species of strongyloid nematodes in the stomach, seven species of trichostrongyloid nematodes in the pylorus and small intestine and seven species of nematodes in the terminal ileum and large intestine, one species of spirurid nematode in the stomach and six species of cestodes and one species of trematode. Forty-three species were encountered in both M. fuliginosus and M. giganteus. The helminth communities of the two kangaroo species exhibited a similarity of 85.4% based on all helminth species encountered or 91.4% if only the species specific to grey kangaroos were considered. Interchange of helminths between the two species of kangaroos revealed several different patterns with instances both of transfer and lack of transfer in areas of host sympatry as well as transfers beyond the zone of sympatry. The findings are discussed in relationship to the phylogeography of the host species.