Ontario provincial by-election, 2007

By-elections were held on February 8, 2007, in Ontario, Canada, to fill three vacancies in the Legislative Assembly of Ontario. By-elections were held in three electoral districts (ridings): Burlington, Markham and York South–Weston.
The by-elections resulted in York South-Weston being taken by the NDP from the Liberals, Burlington remaining Progressive Conservative and Markham being retained by the Liberals.

Since this was a by-election of the 38th Legislative Assembly of Ontario, the ridings used the same boundaries as the 2003 general election. The subsequent October 10, 2007 general election were run on new electoral district boundaries, mostly following the new federal boundaries that were in place for the 2004 and 2006 federal elections.

The Burlington by-election was called following the resignation of Progressive Conservative Member of Provincial Parliament (MPP) Cam Jackson. He resigned to make a successful run in Burlington's 2006 mayoralty election. .