The Microgastrinae (Braconidae: Hymenoptera) comprise the most remarkable group of Lepidoptera parasitoids with respect to economic importance and species diversity. More than 1,500 species worldwide have been described and estimates of actual diversity range between 5,000-10,000. The generic classification of the Microgastrinae has always presented considerable problems and has been impeded by morphological convergence and character reduction. The male genitalia, however, show considerable morphological diversity within the subfamily. We investigate the morphological evolution of the male genitalia as well as a new character system applicable to generic and species levels.