The Blood Transfusion Service Board will present a red carnation to anyone giving blood today, St Valentine's Day.
The board's donor services manager, Ms Helen McGrath, said the gesture was designed to acknowledge that giving blood was one of the most "altruistic" things a person could do.
"It is a completely voluntary, selfless act." Information on the location of the clinics is available on a free-phone number: 1800-731137.