A new delimitation of genera within the nematode family Capillariidae is proposed on the basis of revaluation of the features used in the taxonomy of these nematodes. The following genera are recognized as valid: Schulmanela Ivashkin, 1964 (subgenera Schulmanela Ivashkin, 1964, Piscicapillaria subgen. n. and Amphibiocapillaria subgen. n.), Paracapillaria Mendonça, 1963, Capillostrongyloides Freitas et Lent, 1935, Pseudocapillaria Freitas, 1959 (subgenera Pseudocapillaria Freitas, 1959 and Ichthyocapillaria subgen. n.). Freitascapillaria gen. n., Baruscapillaria gen. n., Liniscus Dujardin, 1845, Pearsonema Freitas et Mendonça, 1960, Capillaria Zeder, 1800, Echinocoleus López-Neyra, 1947, Eucoleus Dujardin, 1845, Pterothominx Freitas, 1959, Aonchotheca López-Neyra, 1947 and Calodium Dujardin, 1845; previously established genera are newly defined. The systematic status of the genera Gessyella Freitas, 1959 and Skrjabinocapillaria Skarbilovich, 1946 has not been so far elucidated. The author newly synonymizes the genera Ritaklossia Freitas, 1959 (= Eucoleus), Armocapillaria Gagarin et Nazarova, 1966 [= Pterothominx) and Hepaticola Hall, 1916 (=Calodium) and the species Hepaticola bakeri Mueller et Van Cleave, 1932 (=Pseudocapillaria catostomi (Pearse, 1924)) and Pseudocapillaria nuda Mendonça, 1963 (= Freitascapillaria maxillosa (Vaz et Pereira, 1934)); many new combinations of specific names are given. A key to the genera and subgenera of the family Capillariidae is provided.