Acidaminococcus fermentans (Rogosa 1969) is the type species of the genus Acidaminococ-cus, and is of phylogenetic interest because of its isolated placement in a genomically little characterized region of the Firmicutes. A. fermentans is known for its habitation of the ga-strointestinal tract and its ability to oxidize trans-aconitate. Its anaerobic fermentation of glu-tamate has been intensively studied and will now be complemented by the genomic basis. The strain described in this report is a nonsporulating, nonmotile, Gram-negative coccus, originally isolated from a pig alimentary tract. Here we describe the features of this organism, together with the complete genome sequence, and annotation. This is the first complete ge-nome sequence of a member of the family Acidaminococcaceae, and the 2,329,769 bp long genome with its 2,101 protein-coding and 81 RNA genes is part of the Genomic Encyclope-dia of Bacteria and Archaea project.