The ability of bacteria from five different granular sludge sources to anaerobically biodegrade aromatic compounds was evaluated. The biodegradabilities of phenol, 4-cresol, 2-aminobenzoate (2-AB) and 5-aminosalicylate (5-ASA) were determined by measuring compound conversion to methane in batch serum bottles at 30oC under agitated conditions over a period of at least 100 days. Phenol and 4-cresol were completely mineralized by all the granular sludges tested. This observation indicates a universal capacity of granular sludge to degrade phenol and 4-cresol; which would be expected since these compounds are intermediates in the anaerobic degradation of the commonly occurring amino acid tyrosine. In contrast, 5-ASA and 2-AB were degraded by only one or two granular sludges. Previous acclimation to an N-substituted aromatic was a prerequisite for 5-ASA degradation.