This study investigates the fate and partitioning of heavy metals in the municipal solid waste (MSW) incinerator ash collected from a typical mass burning incineration plant in Taiwan. The results indicate that large amounts of heavy metals are contributed by noncombustible composition in the MSW. Regarding the partitioning results, Cd and its high vapor pressure compounds were relatively volatile compared to the other trace metals. On average, more than 70% of the Cd was captured in the fly ash, compared to an average of less than 10% of the Cu and Cr. Pb and Zn partitioning was distributed equally between the bottom ash and the fly ash.