Phylogenetic analyses were performed on six genera and 46 species of the Neotropical palm tribe Geonomeae (subfamily Arecoideae) and outgroups composed of 14 species from the Arecoideae, two from the Ceroxyloideae, and one from the Phytelephantoideae. The analyses were based on two low copy nuclear DNA sequences from the genes encoding phosphoribulokinase and RNA polymerase II. The two data sets did not appear to conflict and were analyzed separately and in combination. Our results added support to the previously reported monophyly of the tribe. The basal node of the tribe was polytomous containing the genera Welfia and Pholidostachys and a clade consisting of the rest of the Geonomeae. Pholidostachys formed a monophyletic group. The currently accepted genera Calyptronoma and Calyptrogyne formed a well-supported clade with Calyptronoma resolved as paraphyletic to Calyptrogyne. Geonoma formed a strongly supported monophyletic group consisting of two main clades. Geonoma section Taenianthera was not monophyletic but a group of three high-elevation Geonoma species was resolved. © Copyright 2005 by the American Society of Plant Taxonomists.