The's banks need an extra 24bn euros (£21.2bn) to survive the financial crisis.
The figure follows a stress test on the Irish banking system by a group of independent experts and the country's central bank.
Four lenders were tested - Allied Irish Banks, Bank of Ireland, Educational Building Society (EBS) and the Irish Life & Permanent.
Allied Irish Banks needs most money, and will have to raise 13.5bn euros.
Bank of Ireland needs 5.2bn euros, EBS 1.5bn euros, and Irish Life 4bn euros.
The total amount poured into the Irish banks since the financial crisis will now be close to 70bn euros.
Professor Patrick Honohan, governor of the central bank, said: "The new requirements are needed to restore market confidence, and ensure banks have enough capital to meet even the markets' darkest estimates."
Dublin already owns most of Anglo Irish Bank, Allied Irish Banks and the EBS following previous rescues of the banks.
Mr Honohan said it was likely that, as part of the next infusion of funds, the other two banks to avoid nationalisation - Bank of Ireland and Irish Life & Permanent - would now have be taken into state control.