During a study of the helminths of rodents (Muridae: Hydromyinae) from the island of New Guinea 3 undescribed species of trichostrongyloid nematodes were found. Macrostrongylus ingens n. sp. (Heligmonellidae: Brevistriatinae) occurring in Uromys caudimaculatus (type host), Melomys rufescens, Melomys sp., Paramelomys platyops, Paramelomys cf. platyops, and Paramelomys levipes, could be differentiated from its congener Macrostrongylus ratti by its larger size, shorter spicules, and wider cephalic vesicle. Odilia carinatae n. sp. (Heligmonellidae: Nippostrongylinae) occurring in Uromys anak (type host) and Uromys caudimaculatus differs from all other species of Odilia in the combination of number, form, and arrangement of ridges on the synlophe and the shape of the spicule tips. Odilia implexa n. sp., occurring in U. caudimaculatus (type host) and U. anak is closest to Odilia uromyos in the shape of the spicule tips but has fewer ridges on the synlophe. Macrostrongylus ingens is the first of the Brevistratinae to be recorded from Australasia. Odilia spp. appear, by contrast, to be widely distributed across the region but there is insufficient data to determine the geographical origins of the genus.