Ergasilidae is among the most recorded families of parasitic copepods on fish worldwide. Besides its impressive species richness of 281 species, morphological and genetic phylogenies have demonstrated the lack of monophyly in some genera, as well as other taxonomic deadlocks. This scenario highlights the need to conduct new analysis to better understand the evolutionary history of the family and to improve its systematics. The present analysis comprised 31 ergasilid species plus the outgroup, Hemicyclops tanakai. A morphological matrix containing 27 characters and an alignment of 18S rDNA genetic sequences were used for phylogenetic reconstruction in BEAST 2.5 using Bayesian Inference. The characters and their states were traced in the tree using Tracer. The integrated tree showed a Consistency Index (CI) (homoplasy rate) of 0.55, thus moderately informative. The most informative features (CI>0.60) were the presence of posterolateral processes on cephalosome, segmentation of antennule, terminal armature of antenna and segmentation of leg 4 rami. Species from Neotropical and Ethiopian realms formed distinct lineages, partially supported by morphological traits. Even integrating morphological data, Ergasilus maintained its polyphyletic status, indicating that the current morphological diagnosis does not reflect its real evolutionary history. The same occurred for Neoergasilus. Giving the present results, at least 5 new genera would be erected to allocate Ergasilus spp., but no morphological feature combination appeared to support them. Paraergasilus and Sinergasilus were monophyletic, supported mainly by morphological traits currently used in their diagnosis. The present results reinforced features that must keep distinguishing genera within the Ergasilidae, but also highlighted others, such as segmentation of rami on leg 4, that could also have taxonomic value. Nonetheless, the poor genetic sampling within the family limited the analysis, highlighting that more sequences must be generated to allow the production of more elucidative results in the future.