The influence of initial pH and sulfate concentration on the anaerobic digestion of tannery wastewater was studied using the specific methanogenic activity (SMA) test. The SMA tests were performed with a chemical oxygen demand (COD) concentration of 6.5g/L and SO2 4 concentrations of 1.95, 3.90, 6.50, 8.45 and 10.4g/L. The effect of pH was studied at pH 6.8; 6.4 and 6.1. It was found that methane production took place under all conditions, but the use of SO2 4 concentrations higher than 8.45g/L and initial pH levels lower than 6.4 caused a decrease of up to 73% of methane production. The influence of pH was significant only for SO2 4 concentrations lower than 8.45g/L, with up to 50% inhibition. Specific methanogenic activity for COD/SO2 4 ratios lower than 0.77 depends basically on this ratio and not on the initial pH value under the conditions of the study.