Helminth specimens representing 3 cestode species, an acanthocephalan, and 15 nematode species were collected from the digestive tracts of 30 individuals of Rattus steini (Muridae) from Papua New Guinea. Of the nematode morphotypes, 7 could be identified to species level and there was insufficient material to fully identify the remainder. All were new host records. A bootstrap estimator of species richness indicated that 83.6% of the expected species in the gastrointestinal helminth community of R. steini were recovered. A comparison of the gastrointestinal communities of Rattus leucopus, Rattus giluwensis, Rattus novaeguineae, and Rattus niobe with R. steini found that the dominant elements in each case were heterakids, oxyurids, and spirurids, with heligmonellids at low prevalences and intensities.