The phylogenetic relationships of Pachycereus species and subtribe Pachycereinae were studied using DNA sequence data. A parsimony analysis of chloroplast rpl-16 intron, trnL-F spacer, and internal transcribed spacer (ITS) region were sequenced for 29 species, representing the four genera of subtribe Pachycereinae (Carnegiea, Cephalocereus, Neobuxbaumia and Pachycereus), plus three additional genera of subtribu Stenocereinae, identified as closely related and used as outgroup. Phylogenetic analysis did not support the monophyly of Pachycereus with 12 species, including Anisocereus, Backebergia, Lemaireocereus, Marginatocereus, Mitrocereus and Pterocereus into its synonym. These results support three major clades into Pachycereinae, one defined to Pachycereus hollianus and P. lepidanthus, as the most basal lineage into Pachycereinae species. A second clade was resolved to Cephalocereus and Neobuxbaumia, with Pachycereus fulviceps as sister taxon. The tree topology suggested a third clade to Carnegiea, five Pachycereus species (here refer as sensu stricto), plus other five Pachycereus species as well as Stenocereus aragonii and S. eichalmii.

Key words: Cactaceae, Pachycereeae, Pachycereus, phylogeny