2,134 are sitting the Leaving Cert in the county, a further 2,405 are taking on the Junior Cert.
Minister of State for Training and Skills, Ciarán Cannon, is urging students to try not to get too stressed.
Meanwhile, it's emerged that this year's Leaving Cert has been pre-tested on independent experts.
They've been drafted in to sit the papers by the State Examinations Commission, after what was described as an "unacceptably high" number of mistakes in last year's exams.
It's hoped the subject experts will have spotted any errors before students turn over their papers this morning.