Purpose of this paper is to analyse the possibilities of anaerobic digestion of wastewater si ge and plant biomass mixture. Mesophilic (38±0,5 °C) vertical type biogas digester of 20 liters v. used for experiments. The mixtures of wastewater sludge and grass silage was composed with r~J 3:1; 1:1 and 1:3, therefore the samples of 200 g were prepared and analysed. The highest bio yield from 1 kg total solids of mixture was 963 1/kg at ratio 1:1 and the lowest - 414 1/kg at r 1:3. Methane concentration in biogas was 60,6 % and 116 mg/m3 of hydrogen sulphide.
