Abstract A phylogenetic analysis was conducted to examine the monophyly and relationships of the four broadly defined genera of Aristolochiaceae. Seventy-two morphological characters were coded from representatives of these genera and from a broad selection of potential outgroups. The data support monophyly of the Aristolochiaceae and monophyly of the broadly defined genera Aristolochia, Thottea, and Asarum. The genera are grouped into two clades within the family, Thottea + Aristolochia and Asarum + Saruma. Based on the results of these analyses, Asaroideae, which have been circumscribed by some authors to consist of Saruma, Asarum, and Thottea, are paraphyletic, and should be emended to exclude Thottea.