The phylogeny of the Hydroporinae is investigated in a cladistic analysis emphasizing placement of the genus Peschetius Guignot, historically placed in the tribe Hydroporini. Sixty-nine adult and larval morphological characters were coded for 61 species of Hydroporinae representing eight of the nine tribes. Cladistic analysis of the data resulted in 396 most parsimonious cladograms (length = 176, CI = 46, RI = 80). The results indicate that the genus Peschetius is the sister group to the tribe Bidessini based mainly on an unambiguous character, the presence of a prominent internal spermathecal spine, and several other more ambiguous or homoplasious characters. The tribe Bidessini is expanded to include the genus Peschetius, and it is formally transferred from the tribe Hydroporini. Other results indicating interesting relationships of tribes and genera within Hydroporinae are also discussed. Results include; 1) a dramatically paraphyletic Hydroporini with Laccornellus Roughley and Wolfe, Canthyporus Zimmermann and Hydrocolus Roughley and Larson in basal positions within the phylogeny, 2) Hydrovatus Motschulsky and Queda Sharp resolved as sister groups and not closely related to Methlini van den Branden, 3) support for close relationship of Pachydrus Sharp (Pachydrini Biström, Nilsson and Wewalka) with Hyphydrini Sharp, 4) paraphyly of Hygrotus Stephens sensu lato with the relationship H. (Coelambus) Thomson + (Hygrotus sensus stricto + Hydrovatini)) suggesting recognition of Coelambus and Hygrotus as separate genera, 5) close relationship between the Australian genera of Hydroporini and Hyphydrini and 6) the nesting of Vatellini within a group of Hydroporini.