Most of the recognised genera in Terebellidae lack phylogenetic support because their current diagnoses are based on homoplastic or plesiomorphic features. To address this problem, the phylogenetic relationships of terebellid genera were studied using a morphology-based parsimony analysis of 94 species, with members of the Ampharetidae and Alvinellidae as outgroups. The monophyly of the Terebellidae is supported by the presence of a prostomium shaped as a dorsal ridge-like structure, the prostomial buccal tentacles not retractable into the mouth and the ventral glandular areas having distinct pads. The subfamilies Polycirrinae, Terebellinae and Trichobranchinae are monophyletic. Species of Trichobranchinae form a clade within the Terebellidae, which provides further evidence to support its subfamily status. The lack of evidence to support Thelepodinae reinforces previous statements that this group is not monophyletic
