||The family Heteroderidae is revised. On the basis of shared, derived characters sister groups are established and arranged in a phylogenetic tree. A hypothetical, primitive ancestor for the family is defined. Verutus has a large equatorial vulval slit and is considered to be the most primitive form. Meloidodera developed by a reduction in vulval size. Genera which developed later exhibit a subterminally located vulval slit and progressively lost the annulation of the female cuticle. In this process 4 evolutionary lines emerge: (i) a posterior shift of the vulva and the formation of more or less distinct vulval lips gave rise to Zelandodera and Cryphodera; (ii) changes in the lip configuration of the 2nd-stage juvenile gave rise to Hylonema, Afrodera n.g., Heterodera and Bidera; (iii) changes in the composition of the female cuticle resulted in Thecavermiculatus, Atalodera, Sherodera, Sarisodera and Bellodera n.g.; (iv) a reduction in vulval slit size led to the development of Dolichodera, Globodera, Cactodera and Punctodera. Ephippiodera and Rhizonema are synonymized with Bidera and Sarisodera respectively. Verutus and Meloidodera are recognized as subfamilies Verutinae and Meloidoderinae and the genera in the 4 evolutionary lines are recognized as subfamilies Cryphoderinae, Heteroderinae, Ataloderinae and Punctoderinae respectively. 2 new genera, Afrodera and Bellodera, are erected for species originally described in Sarisodera (S. africana) and Cryphodera (C. utahensis). Both new genera are characterized by a depressed vulval slit and the anus located on the dorsal side of the vulval cone. Differences in lip configuration of the infective juvenile and a postulated difference in female cuticle justifies their placement in different subfamilies. The lip configuration of the infective juveniles in the subfamilies Verutinae, Meloidoderinae, Cryphoderinae, Ataloderinae and Punctoderinae remains basically unchanged. The possible development of this character in the subfamily Heteroderinae is discussed and illustrated. The family Heteroderidae, its 6 subfamilies and 17 genera are defined or redefined, and for each of the genera the nominal species and their synonyms are listed. New synonyms introduced are: Heterodera rumicis and H. scleranthi of H. trifolii; H. ustinova of Bidera avenae; H. mali of Globodera chaubattia. Cactodera acnidae (Schuster & Brezina, 1979) n.comb, and Dolichodera andinus (Golden, Franco, Jatala & Astogaza, 1983) n.comb, are transferred from Heterodera and Thecavermiculatus respectively. Keys are provided for: the subfamilies of the Heteroderidae; the genera of the subfamilies Heteroderinae, Ataloderinae and Punctoderinae; the species of the genera Meloidodera, Heterodera and Bidera. Species inquirendae are listed.