The objective of this work was to study the dynamic leaching behavior of thirty-three elements in municipal solid waste incinerator fly ash using a column test employing double deionized water. Nearly all of the elements initially present in the leachate were found to leach quickly and then decrease to near constant concentrations after five pore volumes of water passed through the column. Of the eight elements subject to toxicity characteristic leaching procedure (TCLP) investigations, all except lead were found in concentrations below regulatory limits. After three pore volumes of water passed through the column, leachate lead concentrations were found to have diminished to TCLP permissible levels. Concerning Resource Conservation and Recovery Act (RCRA) Title D regulations pertaining to permissible landfill leachate production, lead concentrations were still found at levels above allowable limits after as many as 40 pore volumes of leachate production.