In recent years, the biogas system (incubation and stored bags) have been applied widely in the provinces in the Mekong delta improving household's incomes and protecting environments. However, the operation of the biogas system often have a risk due to lacking pig dung when happening diseases or unstable markets. Therefore, study on materials available to replace the pig dung to maintain the operation of the biogas system is really necessary. The research was done to detennine ability of biogas generations in biogas systems from grasses at the household scale. Research results showed that the average amounts of biogas were not significant differences between the control treatI'nents with the pig dung and 3 kinds of grasses, and 7 kinds of grasses with values in term of 5,764 + or - 2082 L, 4,079 + or - 1,294 L, 4,032 + or - 1,906 L. Average amounts of CO2 and other gases (H2S, NH3, ...) did not differ significantly between treatments. However, the amount of CH. generated differently between the control treatment and two treatments of grasses. CH. concentrations fluctuated in range of 39-50 percent, of 34 -39 percent for CO2 and other gases of 16-21 percent. In the present research indicated that orchard grasses could be available and suitable materials to produce biogas in the Mekong delta.