1 The Labor member for Subiaco, Bartholomew James Stubbs, died in action in Belgium on 26 September 1917. At the resulting by-election on 10 November 1917, the Nationalist candidate, Samuel Brown, was successful.
2 The Nationalist member for Claremont, John Stewart, resigned on 30 August 1918. At the resulting by-election on 14 September 1918, the Nationalist candidate, Thomas Duff, was successful.
3 Sir James Mitchell, member for Northam, was appointed by PremierHal Colebatch as Minister for Lands and Repatriation on 17 April 1919. Mitchell was therefore required to resign and contest a ministerial by-election, at which he was declared elected upon the close of nominations on 24 April 1919. He himself became premier three weeks later after the failure of the Colebatch Ministry.
4 The Nationalist member for Albany, Herbert Robinson, died on 2 May 1919. At the resulting by-election on 31 May 1919, the National Labor candidate, former Premier John Scaddan, was successful.
5Thomas Draper, member for West Perth, was appointed by PremierJames Mitchell as Attorney-General on 17 May 1919. Draper was therefore required to resign and contest a ministerial by-election, at which he was successful against an Independent candidate on 7 June 1919.
6Frank Broun, member for Beverley, was appointed by Premier James Mitchell as Colonial Secretary on 25 June 1919. Broun was therefore required to resign and contest a ministerial by-election, at which he was returned unopposed at the close of nominations on 10 July 1919.
Black, David; Prescott, Valerie (1997). Election statistics, Legislative Assembly of Western Australia, 1890-1996. Perth: Parliamentary History Project. ISBN0-7309-8409-5.
Hughes, Colin A.; Graham, B. D. (1976). Voting for the South Australian, Western Australian and Tasmanian Lower Houses, 1890-1964. Canberra: Australian National University. ISBN0-7081-1334-6.