List of Dáil by-elections

By-elections to Dáil Éireann, the house of representatives of the Oireachtas (the legislature of Ireland), occur to fill vacant seats which can be caused by the death, resignation, disqualification or expulsion of a member of the Dáil, known as a Teachta Dála (TD).

Statistical overview

There have been 138 by-elections since 1923, to fill 140 vacancies, including two by-elections to be held on 22 May 2026: the 2026 Dublin Central by-election and the 2026 Galway West by-election. Ninety-three of these were caused by the death of a sitting TD. There were no by-elections during the 3rd, 7th, 9th, 11th, 22nd, 25th and 26th Dála. The longest period without a by-election was almost 10 years between 1984 and 1994. The largest number of by-elections on one day was on 11 March 1925, when seven constituencies filled nine vacancies caused by the National Group's split from Cumann na nGaedheal. Those seven by-elections included two which filled two vacancies, via the single transferable vote. All the other by-elections have used its single-winner analogue, instant-runoff voting.

Twenty-five TDs who were elected at a by-election were not subsequently re-elected at a general election. The only person twice elected at by-elections was Thomas Hennessy.

Timing

Prior to 2011, there was no requirement for a by-election to be held when a vacancy occurred. During the 10th Dáil, after one by-election was held in 1940, no further by-elections were held before the dissolution in 1943, considering difficulties during the Emergency. Writing in 1996, Michael Gallagher gave 521 days as the longest interval between the creation of a vacancy and the holding of the resultant by-election, between the resignation in Mayo West of Pádraig Flynn of Fianna Fáil in January 1993, and the ensuing by-election in June 1994. In April 1993, Proinsias De Rossa of Democratic Left moved motions in the Dáil that the Ceann Comhairle issue by-election writs for both the Mayo West vacancy and a slightly later one in Dublin South-Central. The Fianna Fáil–Labour government defeated the motions,

In November 2010, the High Court granted a declaration that there had been unreasonable delay in holding a by-election in Donegal South-West for a seat which had remained vacant since June 2009. The consequent by-election was held later that month, leading to an interval of days. The Electoral (Amendment) Act 2011 amended the Electoral Act 1992 such that a by-election writ must be issued within six months of the vacancy.

1st and 2nd Dáil

The 1st Dáil was established by Sinn Féin members returned in the 1918 election to the House of Commons of the United Kingdom. Convention in the Commons was that the writ for a by-election be moved by a party colleague of the vacating member, which was impossible for the abstentionist Sinn Féin. There were three by-elections held for Westminster constituencies vacated by Unionist members during the lifetime of the First Dáil, all of whom took their seats in Westminster.

{|class="wikitable"

! colspan=2|Winner

! Party

! Constituency

! Date

! colspan=2|Outgoing

! Party

! Reason for vacancy

! Notes

| Hugh T. Barrie

| U

| North Londonderry

| 4 March 1919

| Hugh Anderson

| U

| Resignation

| This was the only by-election contested by Sinn Féin, Patrick McGilligan losing.

| Ind U

| East Antrim

| 27 May 1919

| U

| Appointed commander of the Irish Guards

| William Jellett

| U

| Dublin University

| 28 July 1919

| Arthur Samuels

| U

| Appointed to the High Court of Justice in Ireland

The 2nd Dáil comprised those returned in the 1921 elections to the House of Commons of Southern Ireland and the House of Commons of Northern Ireland. There were no by-elections to either body during the lifetime of the 2nd Dáil.

By-elections since 1923

By-elections in which seats changed parties are indicated with a grey background.

Vacancies not filled

When Pierce McCan died on 6 March 1919, his East Tipperary seat was left vacant. In April 1919 a Dáil committee considering how to fill the vacancy considered allowing nomination by the Labour Party (which had stood aside in the 1918 election to avoid splitting the nationalist vote) before recommending that the Sinn Féin constituency organisation should nominate. However, in June 1919 the Dáil decided that "it was due to the memory of the late Pierce McCann that his place should not be filled at present". Later vacancies were also left unfilled; when Diarmuid Lynch resigned his seat in 1920, Arthur Griffith said "as the letter of resignation was addressed to the people of South-East Cork, the next step in the matter lay with the South-East Cork Executive of Sinn Fein". Asked in the Civil War about filling 3rd Dáil vacancies, W. T. Cosgrave as Chairman of the Provisional Government stated "the condition of the country scarcely warrants the holding of elections".

In the first Dáil, four Sinn Féin TDs represented two constituencies: Éamon de Valera, Arthur Griffith, Eoin MacNeill and Liam Mellowes. Ordinarily, this would prompt them to choose one constituency to represent, and to move a writ for a by-election in the other constituency.

{|class="wikitable sortable"

! Dáil

! Constituency

! Outgoing TD

! colspan=2|Party

! Reason for vacancy

! Date of vacancy

! Date of dissolution

| 1st

| Death in prison

| 1921 Northern Ireland and Southern Ireland general elections|

| 1st

| Resignation

| 1921 Northern Ireland and Southern Ireland general elections|

| 1st

| Death on hunger strike

| 1921 Northern Ireland and Southern Ireland general elections|

| 1st

| Resignation

| 1921 Northern Ireland and Southern Ireland general elections|

| 2nd

| Waterford–Tipperary East

| Resignation

| 1922 Irish general election|

| 2nd

| Dublin County

| Death

| 1922 Irish general election|

| 2nd

| Longford–Westmeath

| Death

| 1922 Irish general election|

| 3rd

| Waterford–Tipperary East

| Death: Shot during the Civil War