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.^[1] The constituency was previously represented through the constituencies of Roscommon and Longford-Westmeath, both of which were abolished in 1992.

The constituency spanned the entire area of County Longford and County Roscommon, taking in the towns of Longford and Roscommon and many other areas.^[1]

It was one of a number of constituencies which were altered by the Electoral (Amendment) Act 2005; with effect from the 2007 general election, the Longford–Roscommon constituency was abolished. Longford joined the recreated constituency of Longford–Westmeath, while Roscommon became part of Roscommon–South Leitrim.

Note: The columns in this table are used only for presentational purposes, and no significance should be attached to the order of columns. For details of the order in which seats were won at each election, see the detailed results of that election.

• Dáil constituencies
• Politics of the Republic of Ireland
• Historic Dáil constituencies
• Elections in the Republic of Ireland