A sulfate-reducing bacterium (SRB), Desulfovibrio sp. (B strain), isolated from a continuous anaerobic digester (Boopathy and Daniels, Current Microbiology, 23:327-332, 1991) was found to use 2,4,6-trinitrotoluene (TNT) as sole nitrogen source. This bacterium also used nitrate, nitrite, and ammonium as nitrogen source. A long lag period was noticed when TNT or nitrite was used as nitrogen source. Nitrate, nitrite and TNT also served as electron acceptor in the absence of sulfate for this bacterium. Under nitrogen-limiting condition, 100% removal of TNT was observed within 8 days of incubation. The main intermediate observed was diaminonitrotoluene, which was further converted to toluene via triaminotoluene by reductive deamination process. Under nitrogen-rich conditions (presence of ammonium), TNT was converted to diaminonitrotoluene, and toluene was not produced. This isolate did not degrade TNT all the way to CO2. This study demonstrated the possibility of using this isolate to decontaminate the soil and water contaminated with TNT under anaerobic conditions.