The objective of this paper is to evaluate energy and exergy efficiencies of a biogas cogeneration plant. The total and net energy efficiencies for this biogas cogeneration plant were calculated as 91% and 85%, while the total and net exergy efficiencies were 55.5% and 51.7%, respectively. Electric and heat efficiencies and equivalent electrical efficiency of the plant were 37%, 48%, and 80%, respectively. The primary energy savings and relative primary energy savings were found as 264 kW and 22%, respectively. The relative CO2 emissions savings were calculated as 0.62286 kgCO(2)/h for the plant.