The total cost of the project will be around €1.7bn - up from an original estimate of €650m
The chair of the National Paediatric Hospital Development Board is to step down.
The board is responsible for overseeing the building of the new national children's hospital.
Tom Costello says it's due to concerns about "reputational damage" that ongoing commentary about the increased cost of the hospital is causing.
It comes after it was revealed that a review of the rising costs of the hospital was told to stop short of finding individual culpability.
The Oireachtas Public Accounts Committee has heard the total cost of the project will be around €1.7bn - up from an original estimate of €650m.
Every decision made by the board has been guided by what was deemed best
Mr Costello said: "I have acted with professionalism and integrity in all my dealings with the project stakeholders including the Minister for Health and his department.
"Every decision made by the board has been guided by what was deemed best for the project."
"I am concerned about the reputational damage that the ongoing commentary about the increased cost of the hospital is having on this critically important project and so I have decided to step down from my role to help ensure that focus is restored on delivering the project."
Health Minister Simon Harris has accepted his resignation and thanked him for "exceptional commitment" to the project.