Lanark—Frontenac—Lennox and Addington is a provincial electoral district in Ontario, Canada, that has been represented in the Legislative Assembly of Ontario since 2007. The new riding was created in 2003 from parts of Hastings—Frontenac—Lennox and Addington and Lanark—Carleton ridings. In the 2007 provincial election, the MPPs representing the two predecessor ridings of Hastings—Frontenac—Lennox and Addington and Lanark—Carleton chose to run, respectively, in the newly created ridings of Prince Edward—Hastings to the west of the new riding, and Carleton—Mississippi Mills to its east. As a result, the riding had no incumbent, and was contested by candidates who had never previously held office. Progressive Conservative Party of Ontario (PC) candidate Randy Hillier won by a narrow margin of less than one thousand votes, one of only three victories for a PC candidate in a non-incumbent-held riding.