A by-election may be held when a member's seat becomes vacant through resignation, death or some other reasons. These vacancies are called casual vacancies.
Gains for Labor are highlighted in red; for Liberal and its predecessors in blue; and others in grey.
| By-election | Date | Incumbent | Party | Winner | Party | Cause |
|---|
| Cheltenham | 9 February 2019}} | Jay|Weatherill}} | Labor}}| | Labor | Joe|Szakacs}} | Labor}}| | Labor | Resignation |
| Enfield | 9 February 2019}} | John|Rau}} | Labor}}| | Labor | Andrea|Michaels}} | Labor}}| | Labor | Resignation |
| Davenport | 31 January 2015}} | Iain|Evans}} | Liberal}}| | Liberal | Sam|Duluk}} | Liberal}}| | Liberal | Resignation |
| Fisher | 6 December 2014}} | Bob|Such}} | Independent}}| | Independent | Nat|Cook}} | Labor}}| | Labor | Death |
| Ramsay | 11 February 2012}} | Mike|Rann}} | Labor}}| | Labor | Zoe|Bettison}} | Labor}}| | Labor | Resignation |
| Port Adelaide | 11 February 2012 }} | Kevin|Foley|dab=South Australian politician}} | Labor}}| | Labor | Susan|Close}} | Labor}}| | Labor | Resignation |
| Frome | 17 January 2009 | Rob Kerin | Liberal}}| | Liberal | Geoff Brock | Independent}}| | Independent | Resignation |
| Taylor | 5 November 1994 | Lynn Arnold | Labor}}| | Labor | Trish White | Labor}}| | Labor | Resignation |
| Torrens | 7 May 1994 | Joe Tiernan | Liberal}}| | Liberal | Robyn Geraghty | Labor}}| | Labor | Death |
| Elizabeth | 9 April 1994 | Martyn Evans | Labor}}| | Labor | Lea Stevens | Labor}}| | Labor | Resignation (entered HoR) |
| Kavel | 9 May 1992 | Roger Goldsworthy | Liberal}}| | Liberal | John Olsen | Liberal}}| | Liberal | Resignation to provide Olsen a seat. |
| Alexandra | 9 May 1992 | Ted Chapman | Liberal}}| | Liberal | Dean Brown | Liberal}}| | Liberal | Resignation to provide Brown a seat. |
| Custance | 23 June 1990 | John Olsen | Liberal}}| | Liberal | Ivan Venning | Liberal}}| | Liberal | Resignation (entered Senate) |
| Elizabeth | 1 December 1984 | Peter Duncan | Labor}}| | Labor | Martyn Evans | Independent Labor}}| | Independent Labor | Resignation (entered HoR) |
| Bragg | 14 May 1983 | David Tonkin | Liberal}}| | Liberal | Graham Ingerson | Liberal}}| | Liberal | Resignation |
| Florey | 4 September 1982 | Harold O'Neill | Labor}}| | Labor | Bob Gregory | Labor}}| | Labor | Resignation (ill health) |
| Mitcham | 8 May 1982 | Robin Millhouse | Democrats}}| | Democrats | Heather Southcott | Democrats}}| | Democrats | Appointed to SA Supreme Court |
| Norwood | 16 February 1980 | Frank Webster | Liberal}}| | Liberal | Greg Crafter | Labor}}| | Labor | Unseated |
| Norwood | 10 March 1979 | Don Dunstan | Labor}}| | Labor | Greg Crafter | Labor}}| | Labor | Resignation (ill health) |
| Goyder | 8 June 1974 | Steele Hall | Liberal Movement}}| | Liberal Movement | David Boundy | Liberal Movement}}| | Liberal Movement | Resignation (entered Senate) |
| Semaphore | 2 June 1973 | Reg Hurst | Labor}}| | Labor | Jack Olson | Labor}}| | Labor | Death |
| Adelaide | 3 July 1971 | Sam Lawn | Labor}}| | Labor | Jack Wright | Labor}}| | Labor | Death |
| Millicent | 22 June 1968 | Des Corcoran | Labor}}| | Labor | Des Corcoran | Labor}}| | Labor | Unseated |
| Semaphore | 3 October 1964 | Harold Tapping | Labor}}| | Labor | Reg Hurst | Labor}}| | Labor | Death |
| Stirling | 28 September 1963 | William Jenkins | LCL}}| | LCL | William McAnaney | LCL}}| | LCL | Death |
| Yorke Peninsula | 9 February 1963 | Cecil Hincks | LCL}}| | LCL | James Ferguson | LCL}}| | LCL | Death |
| Mount Gambier | 15 December 1962 | Ron Ralston | Labor}}| | Labor | Allan Burdon | Labor}}| | Labor | Death |
| Frome | 5 November 1960 | Mick O'Halloran | Labor}}| | Labor | Tom Casey | Labor}}| | Labor | Death |
| Light | 23 April 1960 | George Hambour | LCL}}| | LCL | Leslie Nicholson | LCL}}| | LCL | Death |
| Mount Gambier | 12 July 1958 | John Fletcher | Independent}}| | Independent | Ron Ralston | Labor}}| | Labor | Death |
| Wallaroo | 3 August 1957 | Leslie Heath | LCL}}| | LCL | Lloyd Hughes | Labor}}| | Labor | Death |
| Mitcham | 7 May 1955 | Henry Dunks | LCL}}| | LCL | Robin Millhouse | LCL}}| | LCL | Death |
| Stirling | 18 October 1952 | Herbert Dunn | LCL}}| | LCL | William Jenkins | LCL}}| | LCL | Death |
| Gawler | 19 April 1952 | Leslie Duncan | Labor}}| | Labor | John Clark | Labor}}| | Labor | Death |
| Flinders | 2 June 1951 | Rex Pearson | LCL}}| | LCL | Glen Pearson | LCL}}| | LCL | Resignation (entered Senate) |
| Rocky River | 26 February 1949 | John Lyons | LCL}}| | LCL | James Heaslip | LCL}}| | LCL | Death |
| Alexandra | 19 June 1948 | Herbert Hudd | LCL}}| | LCL | David Brookman | LCL}}| | LCL | Death |
| Port Pirie | 19 October 1946 | Andrew Lacey | Labor}}| | Labor | Charles Davis | Labor}}| | Labor | Death |
| Semaphore | 5 October 1946 | Albert Thompson | Labor}}| | Labor | Harold Tapping | Labor}}| | Labor | Resignation (entered HoR) |
| Burnside | 22 June 1946 | Charles Abbott | LCL}}| | LCL | Geoffrey Clarke | LCL}}| | LCL | Resignation |
|
| Victoria | 29 September 1945 | Vernon Petherick | LCL}}| | LCL | Jim Corcoran | Labor}}| | Labor | Death |
| Gouger | 10 July 1943 | Albert Robinson | Independent}}| | Independent | Horace Bowden | Labor}}| | Labor | Death |
| Thebarton | 12 December 1942 | Jules Langdon | Independent}}| | Independent | Fred Walsh | Labor}}| | Labor | Death |
| Light | 21 January 1939 | Richard Layton Butler | LCL}}| | LCL | Herbert Michael | LCL}}| | LCL | Resignation (contested HoR) |
| Port Pirie | 3 March 1937 | John Fitzgerald | Labor}}| | Labor | William Threadgold | Labor}}| | Labor | Death |
| Wooroora | 29 September 1934 | Archie Cameron | LCL}}| | LCL | Albert Robinson | Independent}}| | Independent | Resignation (entered HoR) |
| Alexandra | 10 February 1934 | George Laffer | LCL}}| | LCL | George Connor | Independent}}| | Independent | Death |
| Barossa | 8 July 1933 | Herbert Basedow | Independent}}| | Independent | Reginald Rudall | LCL}}| | LCL | Death |
| Victoria | 5 March 1932 | Peter Reidy | Liberal}}| | Liberal | Vernon Petherick | Liberal}}| | Liberal | Death |
| Adelaide | 25 July 1931 | Bert Edwards | Labor}}| | Labor | Martin Collaton | Lang Labor}}| | Lang Labor | Absent without leave |
| Port Adelaide | 2 July 1927 | Thomas Thompson | Protestant Labor}}| | Protestant Labor | Thomas Thompson | Protestant Labor}}| | Protestant Labor | Unseated |
| Adelaide | 21 September 1926 | John Gunn | Labor}}| | Labor | Herbert George | Labor}}| | Labor | Resignation |
| Stanley | 16 March 1926 | Henry Barwell | Liberal}}| | Liberal | John Lyons | Liberal}}| | Liberal | Resignation |
| Yorke Peninsula | 20 January 1926 | Peter Allen | Liberal}}| | Liberal | Edward Giles | Liberal}}| | Liberal | Death |
| East Torrens | 28 November 1925 | Harry Kneebone | Labor}}| | Labor | Walter Hamilton | Liberal}}| | Liberal | Resignation (contested HoR) |
| Port Adelaide | 20 June 1925 | John Price | Labor}}| | Labor | John Stanley Verran | Labor}}| | Labor | Resignation |
| Barossa | 22 November 1924 | William Hague | Liberal}}| | Liberal | Henry Crosby | Liberal}}| | Liberal | Death |
| Alexandra | 20 January 1923 | George Ritchie | Liberal}}| | Liberal | Percy Heggaton | Liberal}}| | Liberal | Resignation |
| Alexandra | 12 June 1920 | Archibald Peake | Liberal}}| | Liberal | Herbert Hudd | Liberal}}| | Liberal | Death |
| Barossa | 2 June 1917 | Ephraim Coombe | Labor}}| | Labor | Henry Crosby | Liberal}}| | Liberal | Death |
| East Torrens | 12 May 1917 | Lionel Hill | Labor}}| | Labor | William Hamilton | Liberal}}| | Liberal | Resignation (contested Senate) |
| Adelaide | 12 May 1917 | John Gunn | Labor}}| | Labor | Bert Edwards | Labor}}| | Labor | Resignation (contested HoR) |
| Newcastle | 12 May 1917 | Thomas Butterfield | Labor}}| | Labor | Edward Twopeny | Liberal}}| | Liberal | Resignation (contested Senate) |
| Alexandra | 19 June 1915 | Alexander McDonald | Liberal}}| | Liberal | Archibald Peake | Liberal}}| | Liberal | Resignation |
| Alexandra | 20 December 1913 | William Blacker | Liberal}}| | Liberal | George Laffer | Liberal}}| | Liberal | Death |
| Murray | 23 November 1912 | William Jamieson | Liberal}}| | Liberal | Harry Dove Young | Liberal}}| | Liberal | Death |
| Torrens | 3 July 1909 | Thomas Price | Labor}}| | Labor | Thomas Ryan | Labor}}| | Labor | Death |
| Wooroora | 13 February 1909 | Friedrich Wilhelm Paech | National Defence League}}| | ANL | Frederick William Young | Farmers and Producers Political Union}}| | FPPU | Death |
| Northern Territory | 5 December 1908 | Vaiben Louis Solomon | National Defence League}}| | ANL | Thomas Crush | Labor}}| | Labor | Death |
| Adelaide | 20 June 1908 | Ernest Roberts | Labor}}| | Labor | Edward Alfred Anstey | Labor}}| | Labor | Resignation |
| Flinders | 18 May 1907 | Arthur Hugh Inkster | Liberal and Democratic Union}}| | LDU | Edgar Hampton Warren | Farmers and Producers Political Union}}| | FPPU | Death |
| Stanley | 13 April 1907 | William Patrick Cummins | Liberal and Democratic Union}}| | LDU | Kossuth William Duncan | Farmers and Producers Political Union}}| | FPPU | Death |
| Adelaide | 26 January 1907 | James Zimri Sellar | Labor}}| | Labor | Reginald Blundell | Labor}}| | Labor | Death |
| Murray | 23 June 1906 | Walter Hughes Duncan | National Defence League}}| | ANL | Hermann Homburg | National Defence League}}| | ANL | Death |
| Victoria and Albert | 25 June 1904 | Andrew Dods Handyside | National Defence League}}| | ANL | William Senior | Labor}}| | Labor | Death |
| Wallaroo | 22 June 1901 | Henry Allerdale Grainger | Other}}| | John Verran | Labor}}| | Labor | Resignation |
| Northern Territory | 15 June 1901 | Vaiben Louis Solomon | Other}}| | Samuel James Mitchell | Other}}| | Resignation (entered HoR) |
| Gumeracha | 8 June 1901 | Thomas Playford IV | Other}}| | William Jamieson | National Defence League}}| | ANL | Resignation (entered Senate) |
| Flinders | 8 June 1901 | Alexander Poynton | Other}}| | William Tennant Mortlock | Other}}| | Resignation (entered HoR) |
| Burra | 8 June 1901 | Frederick Holder | Other}}| | William Russell | Other}}| | Resignation (entered HoR) |
| Barossa | 8 June 1901 | John Downer | National Defence League}}| | ANL | E. H. Coombe | Other}}| | Resignation (entered Senate) |
| North Adelaide | 1 June 1901 | Paddy Glynn | Other}}| | Hugh Robert Dixson | Other}}| | Resignation (entered HoR) |
| West Adelaide | 1 June 1901 | Lee Batchelor | Labor}}| | Labor | Francis Bernard Keogh | Other}}| | Resignation (entered HoR) |
| Northern Territory | 20 October 1900 | Walter Griffiths | Other}}| | Charles Edward Herbert | National Defence League}}| | ANL | Death |
| West Adelaide | 17 March 1900 | Charles Kingston | Other}}| | Bill Denny | Other}}| | Resignation |
| Encounter Bay | 29 July 1899 | Charles Tucker | Other}}| | Charles Tucker | Other}}| | Unseated |
| Mount Barker | 14 May 1898 | John Cockburn | Other}}| | Charles Dumas | National Defence League}}| | ANL | Resignation |
| East Adelaide | 22 January 1898 | John McPherson | Labor}}| | Labor | James Hutchison | Labor}}| | Labor | Death |
| Albert | 31 July 1897 | Archibald Peake | Other}}| | Archibald Peake | Other}}| | Unseated |
| Albert | 22 May 1897 | George Ash | National Defence League}}| | ANL | Archibald Peake | Other}}| | Death |
| North Adelaide | 22 May 1897 | Arthur Harrold | National Defence League}}| | ANL | Paddy Glynn | National Defence League}}| | ANL | Resignation |
| Stanley | 17 October 1896 | Peter Paul Gillen | Other}}| | William Patrick Cummins | Other}}| | Death |
| Gumeracha | 10 July 1896 | Charles Willcox | National Defence League}}| | ANL | William Richard Randell | Other}}| | Resignation |
| North Adelaide | 8 June 1895 | George Charles Hawker | Other}}| | Paddy Glynn | National Defence League}}| | NDL | Death |
| East Torrens | 19 May 1894 | Thomas Playford II | Other}}| | David Packham | National Defence League}}| | NDL | Appointment as Agent General |
| Noarlunga | 26 March 1892 | Charles Dashwood | Other}}| | William Blacker | Other}}| | Death |
|
| East Adelaide | 23 January 1892 | John Cox Bray | Other}}| | John McPherson | Labor}}| | Labor | Resignation |
| Northern Territory | 23 May 1891 | Vaiben Louis Solomon | Other}}| | Vaiben Louis Solomon | Other}}| | Resignation |
| Wallaroo | 23 May 1891 | David Bews | Other}}| | Richard Hooper | Labor}}| | Independent Labor | Death |
| Wooroora | 25 February 1891 | Hugh Craine Kelly | Other}}| | Robert Kelly | Other}}| | Death |
| Yatala | 13 August 1890 | James Cowan | Other}}| | Richard Butler | Other}}| | Death |
| Stanley | 25 June 1889 | Edward William Hawker | Other}}| | Peter Paul Gillen | Other}}| | Resignation |
| Victoria | 1 November 1888 | Daniel Livingston | Other}}| | John James Osman | Other}}| | Death |
| Gumeracha | 12 May 1888 | Robert Dalrymple Ross | Other}}| | Lancelot Stirling | Other}}| | Death |
| East Adelaide | 31 May 1886 | George Dutton Green | Other}}| | Theodor Scherk | Other}}| | Resignation |
| Sturt | 17 July 1885 | Thomas King | Other}}| | Samuel Dening Glyde | Other}}| | Resignation |
| Stanley | 15 May 1885 | John Miller | Other}}| | John Darling, senior | Other}}| | Resignation |
| Wallaroo | 16 February 1885 | Henry Allerdale Grainger | Other}}| | David Bews | Other}}| | Resignation |
| Albert | 5 January 1885 | Rudolph Henning | Other}}| | Andrew Dods Handyside | Other}}| | Death |
| Victoria | 15 June 1883 | George Charles Hawker | Other}}| | William Whinham | Other}}| | Resignation |
| Flinders | 1 December 1882 | Ebenezer Cooke | Other}}| | Patrick Boyce Coglin | Other}}| | Resignation |
| Onkaparinga | 15 June 1882 | Friedrich Krichauff | Other}}| | Rowland Rees | Other}}| | Resignation |
| Yatala | 6 September 1881 | David Murray | Other}}| | Josiah Howell Bagster | Other}}| | Resignation |
| Yatala | 13 July 1881 | David Murray | Other}}| | David Murray | Other}}| | Unseating |
| East Adelaide | 17 June 1881 | George Fowler | Other}}| | Thomas Johnson | Other}}| | Resignation |