The Irish Blood Transfusion Service has suspended taking blood donations from women who have given blood in the last 18 months.
The IBTS says the device used to check haemoglobin levels gives inaccurate results in some people with anaemia.
The service says it will now check samples from each donor for haemoglobin.
In a statement, Health Minister Leo Varadkar said the IBTS has taken precautionary measures to deal with the issue.
The Minister says he is being briefed on the problem and will monitor it closely.
"I am assured that the IBTS has put in place appropriate precautionary, safety, contingency and communication measures to deal with the issue."
Irish Blood Transfusion Service suspends intake from certain donors https://t.co/bgshAySG4L
— RTÉ News (@rtenews) November 16, 2015