This paper describes a study on combustion of livestock wastes for development of a power generation system using them. Broiler, layer and swine excrements are used as fuel. The relationship between calorific value and moisture content is examined. Although moisture content of the prepared livestock wastes shows sufficient fluctuations (10-80 wt%), it does not strongly affect the lower calorific values on a dry basis. The livestock wastes are burned using an established test fluidized-bed furnace. Because moisture content of the swine excrement is very high (80 wt%), swine excrement is mixed with other livestock wastes to decrease the moisture in the fuel. The combustion efficiency, which is defined as the ratio of the heat generation in the fluidized bed to the calorific value of the supplied fuel, is evaluated using a heat balance in the fluidized bed. On the basis of the results, an empirical equation for estimating the combustion efficiency is presented. The fluidized-bed temperatures estimated using the empirical equation and the heat balance almost agree with the experimental ones.