The sintering of incinerator ashes from municipal solid waste was studied considering the compact pressure, sintering temperature, and sinter time. The results indicated that the compressive strength was mainly affected by the compact pressure used in forming the specimens. The strengths of the specimens increased at sintering temperatures from 1120-1140. However, the strength decreased as the ignition loss of incinerator residues increased. As heavy metals are fixed and/or sealed in the sintered incinerator ashes, the process generates a ceramic-like solid of sufficiently low metal leachability. The Pb, Cd, and Cr concentrations of the leachate from the Toxicity Characteristic Leaching Procedure (TCLP) test were 0.10-0.70 mg/l, 0.05-0.30 mg/l, and 0.35-1.25 mg/l respectively, all complying with the regulatory limits of Taiwan EPA. The results suggest the possibility of recycling the incinerator ashes as a construction material by sintering.