Two referendums were held together in the Republic of Ireland on 22 May 1998, each on a proposed amendment of the Irish constitution. Both measures were approved. A referendum in Northern Ireland was also held on the same day.
The Eighteenth Amendment introduced two new articles into the constitution which allowed the government to ratify the Amsterdam Treaty.
|Invalid or blank votes||33,228||2.15|
|Registered voters and turnout||2,747,088||56.20|
The Nineteenth Amendment to the constitution allowed the government to ratify the Good Friday Agreement done at Belfast on 10 April 1998, which included changing articles 2 and 3 of the Irish constitution which effectively claimed Irish sovereignty over Northern Ireland. The agreement was also endorsed in the simultaneous referendum in Northern Ireland. Articles 2 and 3 were subsequently changed in December 1999, and the territorial claim was replaced with an aspiration for a united Ireland to be achieved "by peaceful means with the consent of a majority of the people, democratically expressed, in both jurisdictions in the island".
|Invalid or blank votes||17,064||1.10|
|Registered voters and turnout||2,747,088||56.26|
- "Referendum Results" (PDF). Department of the Environment, Community and Local Government. Archived from the original (PDF) on 24 December 2014. Retrieved 14 August 2014.