Paul Quinn left before a meeting of the National Paediatric Hospital Development Board in August.
Children's Hospital board members thanked Paul Quinn for his service at their meeting at the start of August.
But their minutes DON'T explain why he's quit.
The Chief Procurement Officer is in charge of buying billions of euro worth of goods and services for the public sector -- everything from firefighters' uniforms to new buses.
Mr Quinn is the third member of the National Paediatric Hospital Development Board to quit this year
He follows chairman Tom Costello and Protect Developer John Pollack, who left in the spring.
The board is still waiting to get an update from the main contractor BAM -- and without that it can't do more than estimate the project's cashflow for the months ahead.
The original budget for the Children's Hospital was just €400 million euro -- but it's now spiralled to over €1.7 billion.
Accountants PwC told the government in April there was no guarantee it would stay under two billion.