Biomethanization or biogas production from olive mill solid waste (OMSW) attempted by co-digestion with Turkey manure at mesophilic conditions.A series of laboratory experiments were performed in anaerobic batch operating reactors, fed with mixtures of OMSW and Turkey manure at various concentrations.Anaerobic co-digestion is well-established process for treating solid organic wastes evaluated for biogas (methane) production.The biogas production and some biochemical parameters of anaerobic digestion at 30°C for 40 days were studied as affected by two factors: (a) The type of the animal waste. (b) The ratio of animal waste to OMSW that constitute four levels (100:0 for P1; 80:20 for P2; 60:40 for P3 and 40:60 for P4) of 8%total solid.The total volume of biogas production at P1 was (6247ml), P2 (4316ml), P3 (1847ml) & P4 (1613ml).The results indicated that there was a gradual decrease in total gas productionin the digester by increasing the OMSW ratio, and the highest production was in the first week of the experimentsin all digesters