An enrichment culture that anaerobically degraded m-cresol under sulfate-reducing conditions was obtained from an anoxic aquifer. m-Cresol removal by the culture was greatest when sulfate or thiosulfate served as electron acceptors; sulfite, nitrate, and CO2 were poor substitutes for sulfate. A C-14-labeled carboxylated intermediate was detected when the culture was given C-14-labeled bicarbonate and nonlabeled m-cresol or nonlabeled bicarbonate and C-14-labeled m-cresol. Metabolism of the carboxylated intermediate yielded C-14-acetate, which was eventually converted to (CO2)-C-14. Trace quantities of methylbenzoic acid were also detected as a putative m-cresol intermediate. The importance of this dehydroxylated intermediate in the anaerobic degradation of m-cresol is unclear, since an amendment of 2-methylbenzoic acid was not degraded by the culture. The stoichiometry of electron acceptor consumption and carbon mass balances confirm that m-cresol was mineralized by the culture.