Health Service Executive Director General Tony O'Brien has confirmed that he is to leave his position during the summer.
Mr O'Brien has been Director General since July 2013, having served as Director General Designate/Acting CEO from August 2012.
He was previously Chief Operating Officer of the Special Delivery Unit in the Department of Health and CEO of the National Treatment Purchase Fund (NTPF).
In a statement, Minister for Health Simon Harris said the position of Director General of the HSE "is a vital one" and the lead-in time to Mr O'Brien's departure will allow the recruitment process to begin so that "it can be filled in a timely manner".
Mr Harris paid tribute to Mr O'Brien saying: "I would like to take this opportunity to thank him for his leadership of the organisation for the past six years and his strong commitment to health reform".