Previous understanding of the relationships among the species of bats in the genus Eumops has been primarily based on phenetic and cladistic analyses of morphological genetic similarity data. The objective of this study was to construct a phylogeny using DNA sequence data from 2 mitochondrial loci (cytochrome-b [Cytb] and nicotinamide adenine dinucleotide dehydrogenase subunit 1 [ND1]) and 1 nuclear locus (β-fibrinogen intron 7 [βFib]) for members of Eumops and outgroups from the family Molossidae. Data for each locus were analyzed separately using maximum-likelihood and Bayesian methods and combined for complete data analyses using Bayesian inference and Bayesian concordance analysis on a total of 2,715 base pairs. The monophyly of Eumops was significantly supported in all analyses and molecular dating estimated a most recent common ancestor of the genus at approximately 15.7 million years ago. Placement of E. hansae was problematic, with ND1 analyses supporting a sister relationship with E. patagonicus and E. nanus, whereas Cytb and βFib analyses placed this species as a basal lineage in the genus. Analysis of all genes recovered E. hansae as a poorly supported basal lineage with E. patagonicus and E. nanus as sister to the remaining species. These 3 major lineages of Eumops diverged during the mid-Miocene.