There are just three days of blood supply in most groups across the country.
The Irish Blood Transfusion Service has launched a public appeal for support, as it aims to get 2000 donations over the next five weeks.
It says only 3 percent of the eligible population are blood donors - but that around 1 in 4 people will need a transfusion at some stage in their lives.
The IBTS is asking regular donors to try to attend their nearest clinic, while it's also urging new donors to come forward.
