Grenville—Dundas was a federal electoral district represented in the House of Commons of Canada from 1925 to 1968. It was located in the province of Ontario. This riding was created in 1925 from parts of Dundas and Grenville ridings. It consisted of the counties of Grenville and Dundas. The electoral district was abolished in 1966 when it was redistributed between Grenville—Carleton and Stormont—Dundas ridings.