The optimum conditions of the factors that influence methane production and the utilization of agricultural wastes and digested sludge were studied. The digesters were placed in thermally insulated, heated water baths. The gases were collected in inverted flasks such that the daily monitoring of gas production and composition by gas chromatograph could be achieved. Dilution ratio (weight ratio of water to fresh chicken manure) was found to affect greatly the amount of gas production and dilution ratio of 3-5 was found to be optimal for gas production. The optimal pH ranged from 6.5 to 8.0. At pH below 6.2 gas production was almost negligible. The digestion proceded best at 55$^\circ$C with a thermophilic flora and at 36$^\circ$C with a mesophilic flora. The addition of rice husk on chicken manure gave C/N ratio variation. As the amount of rice husk was increased, gas production increased approximately in production increased approximately in proportion to the amount of rice husk. On a dry solid basis, the chicken manure contained 2.9\% nitrogen, whereas the effluent sludge contained 3.9\% nitrogen by kjeldahl method. Two separate digesters, one for acid fermentation and the other for methane fermentation, were more effective than the batch digester.