By-elections to the 20th Canadian Parliament

By-elections to the 20th Canadian Parliament were held to fill vacancies in the House of Commons of Canada between the 1945 federal election and the 1949 federal election. The Liberal Party of Canada led a working majority government for the 20th Canadian Parliament, though was technically a minority government during World War II.

Shortly before the dissolution of the 20th Canadian Parliament, Newfoundland joined Confederation as the tenth province. Unlike the case when the provinces such as Manitoba, British Columbia and Prince Edward Island joined, by-elections were not called to fill the new province's seven seats.

Eighteen vacant seats were filled through by-elections.

class="wikitable"
By-election	Date	Incumbent	colspan=2 \| Party	Winner	colspan=2 \| Party	Cause	Retained
Nicolet—Yamaska \|February 7, 1949 \|Lucien Dubois \|{{Canadian party colour\|CA\|Independent Liberal\|background}}\| \|Independent Liberal \|Renaud Chapdelaine \|{{Canadian party colour\|CA\|PC\|background}}\| \|Progressive Conservative \|Death \|No
Carleton \|December 20, 1948 \|George Russell Boucher \|{{Canadian party colour\|CA\|PC\|background}}\| \|Progressive Conservative \|George A. Drew \|{{Canadian party colour\|CA\|PC\|background}}\| \|Progressive Conservative \|Resignation to provide a seat for Drew \|Yes
Laval—Two Mountains \|December 20, 1948 \|Liguori Lacombe \|{{Canadian party colour\|CA\|Independent\|background}}\| \|Independent \|Léopold Demers \|{{Canadian party colour\|CA\|Liberal\|background}}\| \|Liberal \|Resignation \|No
Marquette \|December 20, 1948 \|James Allison Glen \|{{Canadian party colour\|CA\|Liberal\|background}}\| \|Liberal \|Stuart Sinclair Garson \|{{Canadian party colour\|CA\|Liberal\|background}}\| \|Liberal \|Resignation \|Yes
Digby—Annapolis—Kings \|December 13, 1948 \|James Lorimer Ilsley \|{{Canadian party colour\|CA\|Liberal\|background}}\| \|Liberal \|George Clyde Nowlan \|{{Canadian party colour\|CA\|PC\|background}}\| \|Progressive Conservative \|Resignation \|No
Algoma East \|October 25, 1948 \|Thomas Farquhar \|{{Canadian party colour\|CA\|Liberal\|background}}\| \|Liberal \|Lester B. Pearson \|{{Canadian party colour\|CA\|Liberal\|background}}\| \|Liberal \|Called to the Senate \|Yes
Rosthern \|October 25, 1948 \|Walter Adam Tucker \|{{Canadian party colour\|CA\|Liberal\|background}}\| \|Liberal \|William Albert Boucher \|{{Canadian party colour\|CA\|Liberal\|background}}\| \|Liberal \|Resignation \|Yes
Ontario \|June 8, 1948 \|W. E. N. Sinclair \|{{Canadian party colour\|CA\|Liberal\|background}}\| \|Liberal \|Arthur Henry Williams \|{{Canadian party colour\|CA\|CCF\|background}}\| \|CCF \|Death \|No
Vancouver Centre \|June 8, 1948 \|Ian Alistair Mackenzie \|{{Canadian party colour\|CA\|Liberal\|background}}\| \|Liberal \|Rodney Young \|{{Canadian party colour\|CA\|CCF\|background}}\| \|CCF \|Called to the Senate \|No
Yale \|May 31, 1948 \|Grote Stirling \|{{Canadian party colour\|CA\|PC\|background}}\| \|Progressive Conservative \|Owen Lewis Jones \|{{Canadian party colour\|CA\|CCF\|background}}\| \|CCF \|Resignation \|No
York—Sunbury \|October 20, 1947 \|H. Francis G. Bridges \|{{Canadian party colour\|CA\|Liberal\|background}}\| \|Liberal \|Milton Gregg \|{{Canadian party colour\|CA\|Liberal\|background}}\| \|Liberal \|Death \|Yes
Halifax \|July 14, 1947 \|William Chisholm Macdonald \|{{Canadian party colour\|CA\|Liberal\|background}}\| \|Liberal \|John Dickey \|{{Canadian party colour\|CA\|Liberal\|background}}\| \|Liberal \|Death \|Yes
Cartier \|March 31, 1947 \|Fred Rose \|{{Canadian party colour\|CA\|Labor-Progressive\|background}}\| \|Labor-Progressive \|Maurice Hartt \|{{Canadian party colour\|CA\|Liberal\|background}}\| \|Liberal \|Seat declared vacant by resolution of the House of Commons \|No
Richelieu—Verchères \|December 23, 1946 \|Arthur Cardin \|{{Canadian party colour\|CA\|Independent\|background}}\| \|Independent \|Gérard Cournoyer \|{{Canadian party colour\|CA\|Liberal\|background}}\| \|Liberal \|Death \|No
Parkdale \|October 21, 1946 \|Herbert A. Bruce \|{{Canadian party colour\|CA\|PC\|background}}\| \|Progressive Conservative \|Harold Timmins \|{{Canadian party colour\|CA\|PC\|background}}\| \|Progressive Conservative \|Resignation \|Yes
Portage la Prairie \|October 21, 1946 \|Harry Leader \|{{Canadian party colour\|CA\|Liberal\|background}}\| \|Liberal \|Calvert Charlton Miller \|{{Canadian party colour\|CA\|PC\|background}}\| \|Progressive Conservative \|Death \|No
Pontiac \|September 16, 1946 \|Wallace McDonald \|{{Canadian party colour\|CA\|Liberal\|background}}\| \|Liberal \|Réal Caouette \|{{Canadian party colour\|CA\|Social Credit\|background}}\| \|Social Credit \|Death \|No
Glengarry \|August 6, 1945 \|William B. MacDiarmid \|{{Canadian party colour\|CA\|Liberal\|background}}\| \|Liberal \|William Lyon Mackenzie King \|{{Canadian party colour\|CA\|Liberal\|background}}\| \|Liberal \|Resignation to provide a seat for Mackenzie King \|Yes

class="wikitable"

By-election

Date

Incumbent

colspan=2 | Party

Winner

colspan=2 | Party

Cause

Retained

Nicolet—Yamaska

|February 7, 1949

|Lucien Dubois