Anaerobic benzene degradation was confirmed in microbial communities enriched from Baltimore Harbor (Baltimore, MD) sediments under methanogenic conditions. Molecular characterization based on 16S rDNA gene sequences revealed that the strains in the communities were diversely affiliated with such phylogenetic branches as the Bacteroidetes, Euryarchaeota, Firmicutes, and Thermotogae phyla. Of interest was that the majority of the microbial populations detected in these cultures were closely related to the members of dechlorinating microbial communities. Further, some of those species were previously found in naphthalene- or phenanthrene-degrading methanogenic communities. Finally, this result could be used to design targeted isolation strategies for anaerobic benzene-degrading strains under methanogenic conditions.