The Irish Blood Transfusion Service (IBTS) says it is "concerned" about supply levels over the Christmas and new year period.
It is urging donors to make a special effort to give blood in the weeks leading up to and over the Christmas season.
From tomorrow until January 8th, the service says it needs more than 12,000 donors to attend its clinics to maintain the blood supply.
To facilitate this, the IBTS is running 30 additional clinics on Sundays and Fridays before and during the Christmas period.
Operations director Paul McKinney says this is to ensure they can meet demand.
"The lead into the Christmas/new year festivities presents significant challenges in sustaining the blood supply.
"Over the Christmas period we are losing 45 clinics and many of these fall on days which are traditionally our busiest days for collecting blood.
"That is why we are arranging extra clinics on Sundays 22nd December, 29th December and January 5th, and Fridays December 27th and January 3rd.
"These clinics are also vital for collecting blood for young babies who can only receive blood no more than five days old since collection."
On any given day, 200 patients receive transfusions in Irish hospitals.
Clinic details can be accessed on the IBTSwebsite, www.giveblood.ie