By-elections to the 33rd Canadian Parliament were held to fill vacancies in the Canadian House of Commons between the 1984 federal election and the 1988 federal election. The Progressive Conservative Party of Canada led a majority government for the entirety of the 33rd Canadian Parliament, though their number did decrease from by-elections. Eleven seats became vacant during the life of the Parliament. Six of these vacancies were filled through by-elections, and five seats remained vacant when the 1988 federal election was called.