There is limited information on naphthalene degradation under denitrifying conditions. In order to further investigate this, denitrifying enrichment cultures were established with sediments collected from two heavily contaminated areas, the Arthur Kill, a heavily contaminated intertidal waterway in the NY/NJ harbor and Onondaga Lake, a freshwater lake in NY state. Based on GC/MS data generated with enrichment cultures, we hypothesize that nitrate-dependent naphthalene degradation proceeds via the anaerobic pathway previously described in sulfidogenic systems. Initial analysis indicated the presence of the metabolites 2-naphthoic acid (2NA) and hexahydro-2-naphthoic acid (HH2NA). 2NA and HH2NA can be used as biomarkers of anaerobic naphthalene degradation by sulfidogenic bacteria in situ. Microorganisms were isolated from active anaerobic consortia enriched from Arthur Kill sediment where naphthalene and nitrate losses were observed. 16S rDNA sequence analysis indicates that the strains isolated are closely related to Stenotrophomonas, Phyllobacterium, Paracoccus, and Azoarcus species. Data suggests that these isolates can utilize naphthalene dissolved in an inert 2,2,4,4,6,8,8 heptamethylnonane (HMN) carrier phase as a sole source of carbon when nitrate is supplied as a terminal electron acceptor. HMN is not metabolized. The nitrous oxide reductase (nosZ) gene has been successfully amplified in all of the isolates, indicating that they have the capability to denitrify. We believe that these isolates will help us understand the mechanism of anaerobic naphthalene degradation and whether the pathway is conserved among organisms that thrive in the absence of oxygen.