The collection of large numbers of nematodes from Macropus rufus from Toganmain and Wilcannia in New South Wales and Cunnamulla in Queensland and from M. canguru from Cunnamulla has made possible the revision of five species and the description of three new species. The work is divided into two sections:(1) Strongylina. Filarinema flagrifer Mönnig, Zoniolaimus setifer Cobb, Z. cobbi Kung, Rugopharynx australis (Mönnig) and Papillostrongylus labiatus Johnston & Mawson are re-described: Pharyngostrongylus alpha Johnston & Mawson and P. beta Johnston & Mawson are recognized as synonyms of R. australis; Filarinema moennigi sp.nov. is described from Macropus rufus.(2) Oxyurina. Macropoxyuris longigularis gen.nov., sp.nov., and M. brevigularis gen.nov., sp.nov., are described from M. canguru. Re-examination of paratype material of oxyurids previously recorded from marsupials has made possible the presentation of more detailed descriptions, and the following nomenclatural changes become necessary: Oxyuris (s.l.) acuticaudata Johnston & Mawson is a synonym of Austroxyuris finlaysoni Johnston & Mawson: Syphacia trichosuri Johnston & Mawson is considered as Oxyuris (s.l.) trichosuri; two new genera are proposed, Potoroxyuris, for Oxyuris (s.l.) potoroo Johnston & Mawson, and Paraustroxyuris for Passalurus parvus Johnston & Mawson. Figures are given of Passalurus ambiguus (Duj.).The material studied was made available by the generosity of Dr R. Mykytowycz of the C.S.I.R.O. Division of Wildlife Research, Canberra, to whom I am most grateful.I am also indebted to Dr R. J. Ortlepp, Division of Veterinary Services, Onderstepoort, South Africa, for the gift of a sample of Rugopharynx australis, to Dr M. J. Mackerras, then of the Queensland Institute of Medical Research, for material from Macropus canguru from centres in south eastern Queensland, and to Dr G. B. Sharman of the C.S.I.R.O. Division of Wildlife Research for information on the correct names of the host species.