The family Muraenidae is one of the largest and most recognizable eel groups. Moray eels are key components of marine ecosystems but their relationships remain poorly understood. The phylogenetic relationships of the morays are examined herein using mitochondrial 12S and 16S sequence data, totaling 1673 bp for 139 taxa. The results of our analyses found support for a monophyletic family Muraenidae that is part of a monophyletic suborder Muraenoidei, which is revised to include the anguilliform families Heterenchelyidae and Myrocongridae, and to exclude the family Chlopsidae. The muraenids form two monophyletic subfamilies, Muraeninae and Uropterygiinae. Of the genera that had multiple species included for analysis, only the type genus of the family, Muraena, is found to be monophyletic. In the subfamily Uropterygiinae, Uropterygius is not recovered as a monophyletic genus. In the subfamily Muraeninae, the species-rich piscivorous genera, Enchelycore and Gymnothorax, and the durophagous genus, Echidna, are demonstrably not monophyletic. The monotypic Gymnomuraena is the sister group to all other muraenine species. The relationships within Muraenidae require much additional study and its genera remain in urgent need of revision. The order Anguilliformes is revised herein to include four suborders: Anguilloidei, Congroidei, Muraenoidei, and Synaphobranchoidei. All four families of the order Saccopharyngiformes are nested within Anguilliformes, recovered as part of a clade that includes Anguillidae; the saccopharyngiform families are referred to the suborder Anguilloidei sensu novum.