The Blood Board says stocks of type O negative and B negative are urgently needed to meet demand.
The Irish Blood Transfusion Service (IBTS) needs to receive 3,000 donations a week, but just 3% of the population give blood regularly.
Andy Kelly, CEO of IBTS, is appealing on World Blood Donor Day for people to make a special effort to donate.
Mr Kelly said: "O negative is a universal donor, anybody can get it in an emergency and that's why it's so use, so we need more people to come in.
"But we need all blood groups to come in, particularly this time of year, because people go on holidays and it might not be in their donation cycle so our supply is poor and coming into the summer that's not a good place to be.
"So we are asking people to make a special effort in this month, it genuinely does save lives and you can't do a greater thing than that."