The anaerobic digestion of the fatty effluents is a biological process, which allows the energy production in the form of biogas. The present study is based on comparing the methanogenic capacity of different inoculum on greasy effluents that result from a restaurant located in Fez city in Morocco. The results showed that the best production of biogas with the inoculum is involved by the one composed of poultry manure and bacterial consortia compared to the other inoculum, during 15 days, the anaerobic digestion of the grease effluent produces 252 cm3 of biogas per gram of grease and achieve an abatement of 92 % as regards the Chemical demand of oxygen (COD) and an elimination of 98 % concerning greases content in the medium. Therefore, the use of anaerobic digester process of grease effluent is shown to be effective and highly gainful for the production of biogas and at the same time decreasing their harmful impact on the environment, therefore the possibility to adopt this process in industrial scale.