Poultry litter is an organic waste in Syria which can be a source of clean energy if treated anaerobically. This research aimed to investigate the effect of mechanical pretreatment of poultry litter in producing biogas and methane. Experiments were performed in units of fermentation laboratory on samples ground spread over parts diameters 1 mm, 3 mm, and 10 mm at at 37°C temperature, for a period of 42 days and compared with untreated samples mechanically.