Iarnród Éireann (Irish pronunciation: [ˈiəɾˠnˠɾˠoːdˠ ˈeːɾʲən̪ˠ], Irish Rail) is the national railway system operator of Ireland. Established on 2 February 1987, it is a subsidiary of Córas Iompair Éireann (CIÉ). It operates all internal intercity, commuter and freight railway services in the Republic of Ireland, and, jointly with Northern Ireland Railways, the Enterprise service between Dublin and Belfast. In 2009, Iarnród Éireann carried 38.8 million passengers, down from 43.3 million in 2008.

As of 2012 Ireland was the only European Union state that had not implemented EU Directive 91/440 and related legislation, having derogated its obligation to split train operations and infrastructure businesses, and allow open access by private companies to the rail network. A consultation on the restructuring of the IÉ is expected to take place in 2012. The derogation ends 14 Mar 2013.

At the time of its establishment Iarnród Éireann referred to itself as Irish Rail, and introduced the four rails IR logo; however, the initials "IR" (Irish Rail) were often defaced as "IRA" on signage.^{[citation needed]} The company gradually brought the Irish form of its name to the fore, ultimately introducing its current IÉ corporate branding and logo in 1994. The Irish word iarnród (alternately rendered "bóthar iarainn") translates into English as iron road, or railway. While the name "Irish Rail" was dropped from the logo, it remains part of the official company name ("Iarnród Éireann - Irish Rail") and was revived as the name of the company's online booking service, irishrail.ie, in 2006.^{[citation needed]}