Helminths, a cestode, and 4 nematode species, including 2 new species and 1 putative new species, were collected from the digestive tracts of 8 Rattus giluwensis (Muridae), and a cestode and 7 nematode species, including 2 putative new species, were obtained from the digestive tracts of 8 Rattus novaeguineae from Papua New Guinea. Heterakis sirawii n. sp. (Heterakidae) most closely resembles Heterakis fieldingi Smales, 1996, and Heterakis dahomensis (Gendre, 1911) but differs from both these species in having ornamentation on the lateral alae, as well as in body size, the dimensions of the precloacal sucker, and egg size. Odilia hagemannae n. sp. (Heligmonellidae) most closely resembles a group of species comprising Odilia emanuelae (Mawson, 1961), Odilia bainae Gibbons and Spratt, 1995, Odilia tasmaniensis Gibbons and Spratt, 1995, and Odilia mamsaensis Hasegawa, Miyata, and Syafruddin, 1999, which have between 17 and 22 ridges on the synlophe at the midbody but differs from each of these species in the detail of the synlophe ridges and the length of the spicules. The nematodes identified from R. giluwensis represented 85.7% of the helminth component community and those of R. novaeguineae 57.5% as calculated using the bootstrap estimator of species richness. Neither assemblage resembled that of any murid endemic to Papua New Guinea that has been studied thus far. The suites of nematodes recovered, however, were closer to that of the new endemic, Rattus leucopus, than those of the older endemic hydromyin murines that have been studied.