Kieran McLoughlin has stepped down as chief executive of the Ireland Funds.
Mr McLoughlin has worked for the organisation for more than 22 years. He was appointed as chief executive in 2010.
The organisation was established by Tony O'Reilly in 1976 to support peace and cultural activities across the island of Ireland.
It has raised more than $600 million (€517 million) for various causes since its foundation, and has chapters in 12 countries.
Mr Mc Loughlin, who is based in New York, has left the organisation to pursue other interests.
In a statement the Ireland Funds confirmed his resignation.
“The Board of Directors of The Ireland Funds has accepted the resignation of Worldwide President & CEO Kieran McLoughlin. We acknowledge McLoughlin’s years of service to the organization, and we respect his decision. The Ireland Funds has begun the search process for a new President & CEO. Caitriona Fottrell will assist with the transition,” the statement said.