Helminths, 3 cestode and 8 nematode species, including 2 new genera, 5 new species, and 1 putative new species, of nematode were collected from the digestive tracts of 23 Lorentzimys nouhuysi (Murinae; Hydromyini) from Papua New Guinea. Odilia wauensis n. sp. (Heligmonellidae) most closely resembles Odilia mallomyos Hasegawa and Syafruddin, 1994, but differs from this species in the detail of the synlophe ridges, the length and tip shape of the spicules, the absence of a gubernaculum, and the size of the eggs. Papuastrongylus kishinamiae n. gen., n. sp. differs from all other genera in the Herpetostrongylidae in the form of the synlophe and spicules, the lack of a gubernaculum, and in being monodelphic. Syphacia lorentzimyos n. sp. and Syphacia mamelonitenuis n. sp. (Oxyuridae) differ from all other species in having a circular cephalic plate and from each other in that S. mamelonitenuis lacks lateral alae. Lorentzicola woolleyae n. gen., n. sp. differs from all other genera in the Oxyuridae (Syphaciini) in having the peribuccal wall with denticles, a simple esophagus, and males with 3 mamelons of the Syphacia type. The helminth assemblage of L. nouhuysi did not resemble that of any other hydromyin rodent from the region studied thus far.