| Donegal South-West | |
| Type: | Dáil |
| Year: | 1981 |
| Abolished: | 2016 |
| Map4: | Donegal South West (Dáil Éireann constituency).png |
| Map Entity: | Ireland |
| Map Size: | 200px |
| Members Label: | TDs |
| Seats: | 3 |
| Local Council Label: | Local government area |
| Local Council: | County Donegal |
| Next: | Donegal |
| Donegal South-West | |
| Type: | Dáil |
| Year: | 1961 |
| Abolished: | 1969 |
| Seats: | 3 |
| Local Council Label: | Local government area |
| Local Council: | County Donegal |
| Next: | Donegal–Leitrim |
Donegal South-West was a parliamentary constituency represented in Dáil Éireann, the lower house of the Irish parliament or Oireachtas, from 1961 to 1969 and from 1981 to 2016. The constituency elected 3 deputies (Teachtaí Dála, commonly known as TDs). The method of election was proportional representation by means of the single transferable vote (PR-STV).
The constituency was first created for the 1961 general election. At the 1969 general election it was abolished and largely replaced by the Donegal–Leitrim constituency. It was recreated for the 1981 general election. It was located in the southern and western parts of County Donegal, it included the towns of Lifford, Donegal, Ballyshannon, Killybegs and Gweedore.[1] It was abolished again at the 2016 general election, and became part of the re-created Donegal constituency.
The Electoral (Amendment) Act 2009 defined the constituency as:
"The county of Donegal, except the part thereof which is comprised in the constituency of Donegal North-East."
Following the resignation of Fianna Fáil TD Pat "the Cope" Gallagher on his election to the European Parliament in June 2009, a by-election was held on 25 November 2010. The seat was won by the Sinn Féin candidate Pearse Doherty.
Following the death of Fianna Fáil TD Clement Coughlan, a by-election was held on 13 May 1983. The seat was won by the Fianna Fáil candidate Cathal Coughlan, brother of the deceased TD.