Phylogenetic relationships within many lineages of the phylum Nematoda remainunresolved, despite numerous morphology-based and molecular analyses. Weperformed several phylogenomic analyses using 286 published genomes andtranscriptomes and 19 new transcriptomes by focusing on Trichinellida, Spirurina,Rhabditina, and Tylenchina separately, and by analyzing a selection of species fromthe whole phylum Nematoda. The phylogeny of Trichinellida supported the divisionof Trichinella into encapsulated and non-encapsulated species and placed them assister to Trichuris. The Spirurina subtree supported the clades formed by species fromAscaridomorpha and Spiruromorpha respectively, but did not support Dracunculoidea.The analysis of Tylenchina supported a clade that included all sampled species fromTylenchomorpha and placed it as sister to clades that included sampled speciesfrom Cephalobomorpha and Panagrolaimomorpha, supporting the hypothesis thatpostulates the single origin of the stomatostylet. The Rhabditina subtree placed a cladecomposed of all sampled species from Diplogastridae as sister to a lineage consistingof paraphyletic Rhabditidae, a single representative of Heterorhabditidae and a cladecomposed of sampled species belonging to Strongylida. It also strongly supportedall suborders within Strongylida. In the phylum-wide analysis, a clade composedof all sampled species belonging to Enoplia were consistently placed as sister toDorylaimia + Chromadoria. The topology of the Nematoda backbone was consistentwith previous studies, including polyphyletic placement of sampled representatives ofMonhysterida and Araeolaimida.