A sequential anaerobic/aerobic treatment process was used to biodegrade the azo dye disperse blue 79 (DB79). The integrated process was successfully tested and operated for the mineralization of the DB79 dye until a concentration of 120 mg/l in 96 h. In the first stage, the anaerobic biofilter biotransformed the DB79 to amines with efficiencies of decolorization higher than 95% in 72 h. The amines produced in the first stage were degraded in the aerobic biofilter with efficiencies of 65% in 24 h. It was observed that the use of a co-substrate on the anaerobic biofilter influenced the performance of the bioreactor only when the concentration of the DB79 was higher than 48 mg/l. It was found that the residual dye in the effluent of the anaerobic stage inhibits the performance of the aerobic microorganisms.