Nematodes from opossums and rodents captured in the Brazilian Atlantic Forest in the State of Rio de Janeiro, Brazil were studied. From the opossums Didelphis aurita Weid-Neuweid, 1826 and Philander opossum (Linnaeus, 1758) the following nematode species were recovered: Viannaia hamata Travassos, 1914, Aspidodera raillieti Travassos, 1913, Cruzia tentaculata (Rudolphi, 1819), Travassos, 1917, Turgida turgida (Rudolphi, 1819) Travassos, 1919, Gongylonemoides marsupialis (Vaz & Pereira, 1934) Freitas & Lent, 1937, Viannaia viannai Travassos, 1914, Spirura guianensis (Ortlepp, 1924) Chitwood, 1938 and from the rodents Akodon cursor (Winger, 1887), Nectomys squamipes (Brants, 1827), Oligoryzomys eliurus (Wagner, 1845) and Oryzomys intermedius (Leche, 1886): Hassalstrongylus epsilon (Travassos, 1937) Durette-Desset, 1971, Syphacia obvelata (Rudolphi, 1802) Seurat, 1916, S. venteli Travassos, 1937, Physaloptera bispiculata Vaz & Pereira, 1935, Litomosoides carinii (Travassos, 1919) Vaz, 1934, Viannaia viannai, Hassalstrongylus epsilon, H. zeta (Travassos, 1937) Durette-Desset, 1971, Stilestrongylus aculeata (Travassos, 1918) Durette-Desset, 1971 S. eta (Travassos, 1937) Durette-Desset, 1971. Highest worm burdens and prevalences were those related to Cruzia tentaculata in marsupials. Stilestrongylus aculeata was referred for the first time in Akodon cursor