The Bank of Ireland (Irish: Banc na hÉireann) (ISEQ: BKIR. LSE: BKIR, NYSE: IRE) is a commercial bank operation in Ireland, which is one of the traditional 'Big Four' Irish banks.

Historically the premier banking organisation in Ireland, the Bank occupies a unique position in Irish banking history. At the core of the modern-day group is the old Bank of Ireland, the ancient institution established by Royal Charter in 1783.

In March 2011 during the Irish banking crisis the bank was found to be in need of an external €5.2 billion bailout.

Bank of Ireland is the oldest bank in continuous operation (apart from 4 closures due to bank strikes, 1950, 1966, 1970, 1976) in Ireland.

From the beginning, it was connected closely with the leading banking family in Dublin, the Huguenot La Touche family. A member of that family – David La Touche – was the first Governor.

The Bank of Ireland is not, and was never, the Irish central bank. However, as well as being a commercial bank – a deposit-taker and a credit institution – it performed many central bank functions, much like the earlier-established Bank of Scotland and Bank of England. The Bank of Ireland operated the Exchequer Account and during the nineteenth century acted as something of a banker of last resort. Even the titles of the chairman of the board of directors (the Governor) and the title of the board itself (the Court of Directors) suggest a central bank status.