The flea beetles (Galerucinae: Alticini) are notable in the lack of taxonomic consensus describing the relationships between the genera and their relationship to the traditional “galerucines”. As the first part of a larger study of the phylogeny of the flea beetles, a phylogeny of the flea beetles using over 100 representative genera from all continents and based on fragments of large and small subunit nuclear ribosomal DNA (18S V7-9 and 28S-D2) and cytochrome oxidase I molecular markers is presented and discussed. Genera from the Galerucinae s.s. and 9 Chrysomelinae genera are also analyzed. Phylogenetic analyses are performed using parsimony and maximum likelihood techniques; the alignment was generated using secondary structural models. Support for the monophyly of the well-recognized taxonomic groups, Oedionychina, Monoplatina and Disonychina is discussed. Support for other groupings previously, recognized or not, is also discussed. Phylogenies resulting from separate and combined analyses of each data set will be presented; the 28S data set offers significant synapomorphies for some clades. Hypotheses describing the loss of Maulik’s organ (the metafemoral apodeme) and evolution of endophagy in the Galerucinae s.l. will be presented and discussed.