Whereas it is generally agreed that the Neotropical bat family Mormoopidae is aligned within the superfamily Noctilionoidea, interfamilial relationships within Noctilionoidea and intrafamilial relationships within Mormoopidae have been debated. DNA sequence data have been generated from a few representatives of Mormoopidae to address interfamilial relationships within Chiroptera, but no such study has focused on relationships within Mormoopidae. Our purpose was to test noctilionoid interfamilial and mormoopid intrafamilial relationships by using a combination of DNA sequence (mitochondrial 12S rRNA, tRNA^Val, 16S rRNA) and morphologic data. Parsimony analysis of the DNA sequence data and the combined molecular and morphologic data strongly support: monophyly of Mormoopidae, Mormoops, Pteronotus, and the subgenus Pteronotus; a sister-taxon relationship between Phyllostomidae and Mormoopidae; and Mystacinidae as sister to the Phyllostomidae and Mormoopidae clade. Although resolution and strong support was provided by this study for several noctilionoid and mormoopid clades, relationships within Pteronotus remain somewhat unclear as monophyly of the subgenus Chilonycertis was weakly supported.