Ratings agency Fitch has upgraded Ireland's credit rating to A from A minus, saying the economy is growing at a "brisk pace".
The agency pointed out that the economy grew last year to the end of September by 7% - the fastest among developed economies.
It said the economy will grow by around 4% this year - up from the 2.4% forecast in its previous assessment.
Ratings are used by investors to help them make decisions on where to put their money.