| By-election | Date | Incumbent | Party | Winner | Party | Cause | Retained |
|---|
| Guysborough | March 16, 1904 | Duncan Cameron Fraser | | Liberal | John Howard Sinclair | | Liberal | Appointed to Supreme Court of Nova Scotia | Yes |
| Gaspé | February 20, 1904 | Rodolphe Lemieux | | Liberal | Rodolphe Lemieux | | Liberal | Recontested upon appointment as Solicitor-General | Yes |
| Lambton East | February 16, 1904 | Oliver Simmons | | Conservative | Joseph Elijah Armstrong | | Conservative | Death | Yes |
| St. Hyacinthe | February 16, 1904 | Michel Esdras Bernier | | Liberal | Jean Baptiste Blanchet | | Liberal | Appointed a Railway Commissioner | Yes |
| City of St. John | February 16, 1904 | Andrew George Blair | | Liberal | John Waterhouse Daniel | | Conservative | Appointed head of the Board of Railway Commissioners | No |
| Bruce East | February 16, 1904 | Henry Cargill | | Conservative | James J. Donnelly | | Conservative | Death | Yes |
| St. James | February 16, 1904 | Joseph Brunet | | Liberal | Honoré Hippolyte Achille Gervais | | Liberal | Election declared void | Yes |
| West Queen's | February 16, 1904 | Donald Farquharson | | Liberal | Horace Haszard | | Liberal | Death | Yes |
| Montmagny | February 16, 1904 | Pierre-Raymond-Léonard Martineau | | Liberal | Armand Lavergne | | Liberal | Death | Yes |
| Hochelaga | February 16, 1904 | Joseph Alexandre Camille Madore | | Liberal | Louis-Alfred-Adhémar Rivet | | Liberal | Appointed Puisne Judge of the Supreme Court of Quebec | Yes |
| Kamouraska | February 12, 1904 | Henry George Carroll | | Liberal | Ernest Lapointe | | Liberal | Appointed a judge | Yes |
| Rouville | January 30, 1904 | Louis-Philippe Brodeur | | Liberal | Louis-Philippe Brodeur | | Liberal | Recontested upon appointment as Minister of Inland Revenue | Yes |
| Westmorland | January 30, 1904 | Henry Emmerson | | Liberal | Henry Emmerson | | Liberal | Recontested upon appointment as Minister of Railways and Canals | Yes |
| Russell | April 20, 1903 | William C. Edwards | | Liberal | David Wardrope Wallace | | Liberal | Called to Senate | Yes |
| Ontario North | March 10, 1903 | Angus McLeod | | Liberal-Conservative | George Davidson Grant | | Liberal | Death | No |
| Maskinongé | March 3, 1903 | Joseph-Hormisdas Legris | | Liberal | Hormidas Mayrand | | Liberal | Called to Senate | Yes |
| Terrebonne | February 24, 1903 | Raymond Préfontaine | | Liberal | Samuel Desjardins | | Liberal | Recontested upon ministerial appointment. Préfontaine was elected in two ridings simultaneously and chose to stand for re-election in Maisonneuve | Yes |
| Two Mountains | February 24, 1903 | Joseph Arthur Calixte Éthier | | Liberal | Joseph Arthur Calixte Éthier | | Liberal | Election declared void | Yes |
| Grey North | February 24, 1903 | Edward Henry Horsey | | Liberal | Thomas Inkerman Thomson | | Conservative | Death | No |
| Burrard | February 4, 1903 | George Ritchie Maxwell | | Liberal | Robert George Macpherson | | Liberal | Death | Yes |
| Maisonneuve | December 9, 1902 | Raymond Préfontaine | | Liberal | Raymond Préfontaine | | Liberal | Recontested upon appointment as Minister of Marine and Fisheries | Yes |
| Argenteuil | December 3, 1902 | Thomas Christie | | Liberal | Thomas Christie, Jr. | | Liberal | Death | Yes |
| Yarmouth | December 3, 1902 | Thomas Barnard Flint | | Liberal | Bowman Brown Law | | Liberal | Appointed Clerk of the House of Commons | Yes |
| Yukon | December 2, 1902 | New Seat | | | James Hamilton Ross | | Liberal | Newly created electoral district under The Yukon Territory Representation Act 1902 | N.A. |
| Beauharnois | March 26, 1902 | George di Madeiros Loy | | Liberal | George di Madeiros Loy | | Liberal | Election declared void | Yes |
| Kamouraska | February 28, 1902 | Henry George Carroll | | Liberal | Henry George Carroll | | Liberal | Recontested upon appointment as Solicitor General | Yes |
| Lisgar | February 18, 1902 | Robert Lorne Richardson | | Independent | Duncan Alexander Stewart | | Liberal | Election declared void | No |
|
| Quebec West | January 29, 1902 | Richard Reid Dobell | | Liberal | William Power | | Liberal | Death | Yes |
| Oxford North | January 29, 1902 | James Sutherland | | Liberal | James Sutherland | | Liberal | Recontested upon appointment as Minister of Marine and Fisheries | Yes |
| Victoria | January 28, 1902 | Edward Gawler Prior | | Conservative | George Riley | | Liberal | Election declared void | No |
| Laval | January 15, 1902 | Thomas Fortin | | Liberal | Joseph-Édouard-Émile Léonard | | Conservative | Appointed a judge of the Superior Court of Quebec | No |
| Addington | January 15, 1902 | John William Bell | | Conservative | Melzar Avery | | Conservative | Death | Yes |
| Durham West | January 15, 1902 | Charles Jonas Thornton | | Liberal | Robert Beith | | Conservative | Election declared void. | No |
| St. James | January 15, 1902 | Odilon Desmarais | | Liberal | Joseph-Édouard-Émile Léonard | | Liberal | Appointed a judge of the Superior Court of Quebec | Yes |
| York West | January 15, 1902 | Nathaniel Clarke Wallace | | Conservative | Archibald Campbell | | Liberal | Death | No |
| L'Islet | January 15, 1902 | Arthur Miville Déchêne | | Liberal | Onésiphore Carbonneau | | Liberal | Called to the Senate | Yes |
| West Queen's | January 15, 1902 | Louis Henry Davies | | Liberal | Donald Farquharson | | Liberal | Appointed a justice of the Supreme Court of Canada | Yes |
| Kingston | January 15, 1902 | Byron Moffatt Britton | | Liberal | William Harty | | Liberal | Appointed a judge of the Court of King's Bench for Ontario | Yes |
| Hastings West | January 15, 1902 | Henry Corby | | Conservative | Edward Guss Porter | | Conservative | Resignation | Yes |
| Beauce | January 8, 1902 | Joseph Godbout | | Liberal | Henri Sévérin Béland | | Liberal | Called to the Senate | Yes |
| York | December 28, 1901 | Alexander Gibson | | Liberal | Alexander Gibson | | Liberal | Election declared void | Yes |
| East Queen's | March 20, 1901 | Donald Alexander MacKinnon | | Liberal | Donald Alexander MacKinnon | | Liberal | Election declared void | Yes |
| Bruce North | March 20, 1901 | Alexander McNeill | | Liberal-Conservative | James Halliday | | Conservative | Election declared void | Yes |