Blood Group Basics
Classifications
There are eight blood groups and they are classified using two systems.
ABO System
The first system is called the ABO System and it has four main groups:
- O Group
- A Group
- B Group
- AB Group
Rhesus System
The second system is called the Rhesus System and is classified as Rhesus Positive (+) and Rhesus Negative (-). The two systems combine to define the following of eight different blood groups of O-, O+, A-, A+, B-, B+, AB- and AB+.
Blood Group Compatibility
The table below demonstrates blood type compatibility. A person with AB+ blood type can receive blood from all of the major blood type groups. At the other extreme people with O- blood type can only receive blood from donors with the same blood type.
| Blood Group | Gives to these groups | Receives from these groups |
|---|
 | All | O- only |
 | AB+, A+, B+, O+ | O- and O+ |
 | AB-, AB+, A+, A- | O- and A- |
 | AB+ and A+ | O-, O+, A-, A+ |
 | B-, B+, AB-, AB+ | O- and B- |
 | B+ and AB+ | O-, O+, B-, B+ |
 | AB- and AB+ | O-, A-, B-, AB- |
 | AB+ only | All |
Irish Blood Group Type Frequency Distribution
Blood group O Positive is the most common group in Ireland while AB negative is the least common.
| Blood Group | Percentage |
|---|
| 47 |
| 26 |
| 9 |
| 8 |
| 5 |
| 2 |
| 2 |
| 1 |
Current Blood Supply
View the Current Blood Supply here.