The former Rehab chief executive Angela Kerins will not be attending tomorrow's meeting of the Public Accounts Committee.
Ms Kerins' solicitors have told the Committee that the former CEO will not be attending on medical advice, due to ill health.
The committee is to hold a second hearing on Rehab tomorrow, to discuss its use of more than €80m in public funding.
TDs have not yet been told whether Ms Kerins' predecessor Frank Flannery plans to attend.
The group's chairman Brian Kerr is due to attend, along with the chief financial officer and the chairman of Rehab's remuneration committee.
Ms Kerin's predecessro Frank Flannery