Career
He was a physician by career. He was first elected at the Québec—Montmorency riding in the 1962 general election then re-elected in 1963. Marcoux became an independent candidate in the 1965 election with Henri Borgia as the Ralliement créditiste candidate.
However, Marcoux was defeated at Québec—Montmorency by Ovide Laflamme of the Liberal party.