The HSE has said it is checking medical records to see how many patients were operated on using instruments which had been used on a patient who has been diagnosed at Beaumont Hospital with Creutzfeldt-Jakob disease.
The fatal degenerative brain disease can be passed on through contaminated surgical instruments.
If instruments are used on a patient with CJD, international guidelines say they must be put through a special highly rigorous sterilisation procedure or destroyed.
Normal sterilisation techniques are not sufficient.
It is understood the operation on the patient with CJD happened around two weeks before their recent diagnosis.
The instruments were not isolated until the diagnosis and were used on other patients before then.
It is not known how many patients are involved, but it is believed to be between ten and 20.
Those patients will be contacted and will have to be monitored indefinitely.
In a statement, the HSE said: "Beaumont Hospital is receiving advice from the Irish Panel on TSE (CJD) and from world experts in the UK, who have dealt with similar cases in the UK and worldwide.
"This group is assessing the circumstances of this case to determine what, if any, risk may exist for other patients."
Beaumont Hospital issued a statement saying: "The primary concern of Beaumont Hospital is for its patients and their care.
"Until the necessary risk assessment is completed and the necessary contact made with patients, it is not in a position to discuss the issues under review.
"While the number of patients potentially affected is low and confined to one area of surgery, Beaumont will have a helpline (1800 302 602) open from 8am to respond to concerned patients."