Health and social services' watchdog HIQA has appointed its Director of Regulation Phelim Quinn as acting Chief Executive.
The appointment is pending the filling of the post vacated by Tracey Cooper last May.
Dr Cooper, who served for seven-and-a-half years as the organisation's first chief executive, stepped down to become Head of Public Health in Wales.
Mr Quinn takes up the role today following the retirement of Professor Jane Grimson who had occupied the post.
Chairperson of the HIQA Board Brian McEnery said it hopes to be in a position to appoint a chief executive "over the coming months".
He vowed that, in the interim, HIQA would remain "very focused on its work and on people using its services".
Mr Quinn expressed his delight at having been asked to continue and build on Dr Cooper's and Professor Grimson's work.
He said HIQA is committed to following through on the work programme outlined in its corporate plan for 2013-2015.
He continued: "Central to the successful delivery of this programme is our fundamental commitment to transparency and independence that puts the people who use our health and social care services at the heart of what we do.
"The authority has and will always act in the best interests of the public to drive safer, better care.
"We will continue to work towards improving the quality, safety and effectiveness of health and social care services for the people of Ireland and to support informed decisions on how services are delivered."
