Phylogenetic relationships of the 11 families and 35 genera of deep-sea anglerfishes of the lophiiform suborder Ceratioidei, characterized most strikingly by an extreme sexual dimorphism that extends to all taxa, were analyzed on the basis of 71 morphological characters applicable to metamorphosed females. All characters were treated as unordered and unweighted, and were polarized by outgroup comparison with taxa of the lophiiform suborders Lophioidei, Antennarioidei, Chaunacoidei, and Ogcocephaloidei. The analysis produced five equally parsimonious trees, with a total length of 153, a consistency index of 0.5560, and a retention index of 0.7952. Lack of resolution was totally attributed to a single family, the relatively poorly understood Oneirodidae, containing 16 genera and 65 species, nearly 40% of all recognized ceratioids. Monophyly for the Ceratioidei was confirmed and all ceratioid genera were placed in currently recognized monophyletic families. Sister families Centrophrynidae and Ceratiidae were found to be basal in position relative to all other ceratioids. The Himantolophidae, Diceratiidae, and Melanocetidae diverge next in sequential step-wise fashion, the latter family forming the sister group of all remaining ceratioids. The integrity of the Thaumatichthyidae to include both Lasiognathus and Thaumatichthys was maintained, this family forming the sister group of the Oneirodidae. Contrary to its basal position in most all previously proposed hypotheses, the Caulophrynidae was found to be deeply embedded within the suborder, forming the sister group of a monophyletic assemblage containing the Gigantactinidae, Neoceratiidae, and Linophrynidae. Sister families Gigantactinidae and Neoceratiidae were found to form the sister group of the Linophrynidae. A second analysis, with characters of metamorphosed males and larvae added to the matrix, resulted in a collapse of several of the deeper nodes of the tree (because of incomplete sampling; males are unknown for eight of the 30 ceratioid genera available for analysis, and larvae are unknown for nine), producing 352 equally parsimonious trees with a total length of 202. Mapping modes of reproduction on the resulting trees reaffirmed the hypothesis that sexual parasitism has evolved independently more than once within the suborder and perhaps as many as seven times. Whether facultative parasitism and temporary attachment of males to females are precursors to obligate parasitism, or the former are more derived states of the latter, remains unknown.