Male genitalia have been widely used in taxonomy and phylogenetic analysis in most groups of insects. However, except in a few groups, taxonomists have widely overlooked or neglected the significance of female genitalia for phylogenetic analysis. The female genital plates of 26 species in four genera of East Asian Panorpidae (Mecoptera) were investigated using light and scanning electronic microscopy. The phylogeny of these species was analysed with maximum parsimony based on characters derived from the female genital plates, in combination with other characters, employing Brachypanorpa carolinensis and Panorpodes kuandianensis (Panorpodidae) as outgroups. The results show that the female genital plate of the Panorpidae is a reliable character both for species delimitation and phylogenetic analysis. The monophyly of the genus Sinopanorpa is well supported in the topology. The genus Panorpa is reconfirmed to be paraphyletic and probably deserves subdivision. Notably, the P. amurensis, P. centralis (= P. cornigera group), and P. diceras groups are evidently monophyletic and might merit generic or subgeneric status. However, the P. davidi group is definitely paraphyletic and needs further systematic study. The origins and evolutionary pathway of the female genital plate of the Panorpidae are briefly discussed. [ABSTRACT FROM AUTHOR]