Nucleotide sequences of the plastid locus ndhF are used to examine phylogenetic relationships among 25 representative species of subfamily Tillandsioideae. Genetic divergence among bromeliad taxa is low for ndhF sequences, ranging from 2.1% between Catopsis zvangerinii and Tillandsia tricholepis, to 0.2% between several species of Guzmania, Mezobromelia, and Vriesea. Parsimony analysis produced six shortest trees of 216 steps. These results: 1) suggest Tillandsioideae as traditionally circumscribed is monophyletic; 2) place Catopsis and Glomeropitcairnia in a clade that is the sister group to the remainder of the subfamily; 3) indicate Vriesea is a paraphyletic grade from within which Tillandsia and Guzmania have arisen, and 4) suggest Mezobromelia is more closely related to Vriesea subg. Vriesea sect. Xiphion than its traditionally recognized sister-group, Guzmania. All subgenera and sections of Tillandsia and Vriesea for which at least two taxa are sampled are paraphyletic. ndhF sequences support sister-group relationships for Tillandsia utriculata (subg. Tillandsia) and Vriesea espinosae (subg. Vriesea sect. Vriesea), as well as for Tillandsiafutnckiana (subg. Tillandsia) and Vr-iesea malzinei (subg. Vriesea sect. Xiphion). Other clades well supported by these data include Tillandsioideae sensu stricto (excludes Catopsis and Glomeropitcairnia) and a component of Vriesea subg. Vriesea sect. Xiphion. Poor resolution and weak branch support for many clades in the ndhF trees suggests that information from more highly variable sequences or the combining of data sets will be required for a clearer understanding of phylogenetic relationships in Tillandsioideae.