Workers will be entitled to build up paid annual leave while they are on long term sick leave under new legislation.
Minster of State for Business and Employment Ged Nash said that under the amendments to the Organisation of Working Time Act, workers will be able to carry over such accrued annual leave for up to 15 months after the leave year in question.
The new rules are being implemented following recent rulings in the Court of Justice of the European Union.
If an worker's employment is terminated, payment in lieu of the untaken annual leave will apply.
Minister Nash said the new laws would protect vulnerable workers.
"We are striking the right balance between protecting the rights of vulnerable workers who are ill and trying to minimise the cost to business and the Exchequer, as well as implementing the requirements of the EU Directive on Working Time."
SIPTU's Patricia King said the new annual leave rules were a positive step.
She said: "It will mean that somebody who has been on sick leave recovering from an illness will now be able to avail of a normal annual leave entitlement without having to wait a lengthy time for that leave to apply to them."
ICTU spokesperson Esther Lynch said: "This legislation beings in an important change for those workers that have been out sick for a long period of time.
"It gives workers in Ireland the same rights as everybody all over Europe. What the change will mean is that you have your holidays as if you were working for the period where you were out sick..."