Hospitals may have to start cancelling surgeries if there isn't an increase in people giving blood over the coming weeks.
The Irish Blood Transfusion Service says there's currently 3 days of stock - compared to the usual 7 days' worth.
It's asking donors to book appointments to give blood to help get supplies back to normal levels.
Operations director with the IBTS, Barry Doyle, hopes hospitals won't have to cancel procedures.
"If we don't get an increase in our stocks which we are hoping for in our appeal, it could happen that we would have to cancel surgeries.
"Obviously we are doing everything we can to avoid that."
