Bus Éireann is to cut 320 jobs and its fleet is to be reduced by 150 vehicles.
The company informed its 2,700 employees of the decision earlier today.
Bus Éireann also outlined a cost effectiveness plan with measures it says are necessary to ensure its success in 'a very challenging economic environment'.
In addition to the job cuts and reduction in its fleet, the plan includes a pay freeze up to the end of 2009 as well as the deferring of payment of the terms of Towards 2016.
In 2007 the company made a profit of €7m but last year it had losses of €9m and that figure was projected to reach €30m in 2009.
The company says that the 'unprecedented economic downturn' led to a 4% decrease in Bus Éireann customer numbers in 2008.
It estimates that there will be a further 5% to 6% fall in passenger numbers in 2009.
Bus Éireann says it hopes that savings from the plan will restore the company to a strong financial position by the end of 2010.
Last week, Dublin Bus announced 290 jobs as part of a series of cost-cutting measures.
Dublin Bus is also withdrawing 120 buses, which is 10% of its fleet.
It said no routes will be removed, but some services would be amalgamated and that the frequency of buses would be adjusted in some areas.