Longford–Roscommon was a parliamentary constituency represented in Dáil Éireann, the lower house of the Irish parliament or Oireachtas from 1992 to 2007.
The constituency was served by 4 deputies (Teachtaí Dála, commonly known as TDs).
The method of election was proportional representation by means of the single transferable vote (PR-STV).
The Longford–Roscommon constituency was created under the Electoral (Amendment) Act 1990 and first used at the 1992 general election.
Longford joined the recreated constituency of Longford–Westmeath, while Roscommon became part of Roscommon–South Leitrim.