The dechlorination of polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins was examined in an enrichment culture (KFL culture) that contained two phylotypes of Dehalobacter, FTH1 and FTH2. The KFL culture dechlorinated 2,3,4,5-tetrachlorobiphenyl, 2,3,4-trichorobiphenyl (2,3,4-TriCB), and 1,2,3-trichlorodibenzo-p-dioxin (1,2,3-TriCDD). Quantitative real-time PCR targeting FTH1 and FTH2 revealed significant increases with the addition of PCBs and 1,2,3-TriCDD, suggesting halorespiring growth of the Dehalobacter species in the KFL culture. This study demonstrated the reductive dechlorination of PCBs and 1,2,3-TriCDD by Dehalobacter species in a sediment-free culture and a novel dechlorination pathway, the conversion of 2,3,4-TriCB to 4-monochlorobiphenyl via 3,4-dichlorobiphenyl.