Aim of this study determine the optimum conditions for producing biogas by co-digestion of cattle manure, chicken waste and cheese whey. The amount of cattle manure was kept constant and chicken waste and cheese whey was fed at different organic loading rates. The system was operated on batch mode under mesofilic (38 degrees C) conditions. Effect of stirring speed on the biogas yield was evaluated at the same time. Results show that maximum biogas yield was obtained from R6 which contains of % 50 cattle manure, % 25 chicken waste and % 25 cheese whey. Maximum biogas yield was obtained 0,142 liter/liter. day and was observed continuously stirring of the wastes didn't have a positive impact.