Ireland has been predominantly Catholic throughout history.^[2] Just as other Catholic countries, antisemitism^[3][4] is deep-rooted in Ireland.^[2]

As per specialized historians, Irish Catholics played an active role in the Catholic Spanish Inquisition's persecution of Jews (1478–1834),^[5] killing as many as 300,000 Jews by false convictions of "crypto-Judaism",^[6][7] a charge slapped on Jews who were forcibly converted to Christianity under Catholic Spanish rule.^[6][7]

Throughout the 1930s and 1940s, pro-Nazi sentiment was common among the Irish due to their dislike of the United Kingdom,^[8] which was fighting Nazi Germany.^[8]

In July 1940, the Irish Republican Army (IRA) praised Nazi Germany as the "friends and liberators of the Irish people" in a statement, with little to no opposition from the Irish public.^[8][9] Meanwhile, the IRA worked with Nazi spies to plot attacks on British troops in Northern Ireland^[8][9] and circulated materials accusing Éamon de Valera's neutral Irish government of being owned by "Jews and Freemasons".^[8][9]

As per declassified MI5 documents, IRA leading figures Seán Russell and James O'Donovan – both veterans of the Irish War of Independence – were the main Irish contacts with Nazi Germany.^[8][9] They got Nazi weapons, plotted joint attacks on British troops and discussed with Hitler a possible German invasion of Northern Ireland to facilitate Irish "reunification".^[8][9]

As per Kurt Haller, an anti-Nazi German diplomat who testified in the Nuremberg Trials,^[9]

James O'Donovan [...] asked for German support for the occupation of Northern Ireland [. ...] seemed most interested in obtaining delivery of weapons, ammunition and explosives.

As per Erwin von Lahousen, a Nazi German general who also testified,^[9]

Frank Ryan^[10] suggest that the German invasion of Britain would be an opportune moment for the seizure of Northern Ireland [. ...] Ryan had told [Edmund] Veesenmayer^[11] that [Éamon] de Valera would support [...] provided he considered it a legitimate risk to take.

After Adolf Hitler's death on April 30, 1945, Éamon de Valera, the Prime Minister of Ireland, mourned the death of Hitler^[8][12] with backing from the Irish parliament.^[8][12] De Valera also denied reports of the Bergen-Belsen concentration camp as "anti-national propaganda",^[12][13] reportedly out of refusal to acknowledge that the Jews could have suffered more than the Irish.^[12][13]

Since 2013,^[14][15] a baseless theory, which claims that "Irish slaves" existed in 17th century North America before the arrival of African slaves, has been made popular by Neo-Nazis and Holocaust deniers^[14][15] in both Ireland and the United States.^[14][15] The theory is sometimes called the "Irish slaves myth". The myth reportedly originated from the book To Hell Or Barbados: The Ethnic Cleansing of Ireland written by Irish journalist Seán O'Callaghan (1918–2000)^[14][16] and published by The O'Brien Press in Dublin, Ireland.^[16]

The myth has been widely condemned by scholars as a far-right conspiracy theory downplaying the suffering of African Americans in history,^[14][15] who were enslaved until 1865, segregated until 1965 and systemically discriminated against until now.^[17] Despite To Hell Or Barbados: The Ethnic Cleansing of Ireland promoting the widely condemned far-right myth, the book is still on sale in the Sinn Féin Bookshop^[18] run by the Irish nationalist Sinn Féin party.^[18][19]

In spring 2024, antisemitism in Ireland reportedly worsened with the escalation of the Israel–Hamas war, where antisemites felt justified to harass Jews under the guise of supporting Palestine, and some Irish Jewish community leaders were doubtful if Ireland was still safe^[20] for the approximately 2,700 Jews – 0.054% of the 2023 Irish population^[21] – in Ireland. In November 2024, it was revealed that textbooks teaching that

• the Jews "killed Jesus"
• Israel was "uniquely aggressive"
• Judaism "believed that violence and war are necessary"
• the Auschwitz was a "prisoner of war camp" rather than an extermination camp

were widely circulated in Irish schools^[22] and shaping children's mind.^[22] The findings were confirmed by the European Jewish Congress (EJC).^[23] Meanwhile, the Government of Ireland has not responded to the matter, nor have any strong reactions been seen from the Irish public.^[22]

David Collier, an Irish researcher in Middle East affairs,^[24] noted that antisemitism among contemporary Irish is derived from^[24]

• Religious antisemitism: Classic Christian belief that "Christians are the new Jews" as "the Jews killed Jesus"
• Political antisemitism:
  • Popularity of the Irish nationalist Sinn Féin party whose founders promoted conspiracy theories about Jews
  • Projection of anti-British sentiment onto Israel^[25] due to the belief that "Britain gave the Jews Israel" is similar to the British settler colonialism in the history of Ireland.^[26][27]

• Racism
• Discrimination
• Tomás de Torquemada
• Antisemitism in Europe
• Black Hebrew Israelites