Blood donation clinics across Dublin and around the country have re-opened after they were forced to close last week because of the snow storm.
Clinics were cancelled, meaning donors were unable to give blood for a number of days during the severe weather.
Paul McKinney, Director of the Irish Blood Transfusion Service, said the national blood supply "has been severely depleted over the last week", and warned that there is current "just 3 days supply on average across all groups and just 2 days in O negative."
"We will be unable to guarantee supply to hospitals unless there is a significant increase in donations over the coming weeks to make up the shortfall", he said.
Those eligible are being encouraged to make an appointment to donate blood, especially in the run up to the Saint Patrick’s Day bank holiday weekend and Easter.
The Irish Blood Transfusion Service is aiming to collect 7,000 donations between now and St Patrick’s weekend.
All clinic details are available on www.giveblood.ie