To determine the concentration and behavior of fine particulate matter (PM2.5) from municipal solid waste incineration, size-classified dust samples were collected from four incineration facilities using cascade impactors. The total dust and PM2.5 concentrations were 1.7-236 and 0-104 mu g/Nm(3), respectively, in the flue gas sampled from the stacks. The total dust concentration in the flue gas was 1/50 or less of the concentrations measured previously in the same facilities with the operation of an electrostatic precipitator. Each air pollution control device used in the facilities was evaluated from the perspective of PM2.5 removal. A bag filter, activated carbon tower and selective catalytic reduction were all considered to be effective. The removal efficiency of PM2.5 was more than 99.99 %. Analysis of the particle size distributions of the dust identified two peaks around 1 and 10 mu m at the inlet of the BF. Based on the results of an elemental analysis of the dust, the particle size distributions of each element were also calculated. As a result, the emission of PM2.5 as primary particles from a state-of-the-art municipal solid waste incinerator was estimated to be very low.