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Blood Group Basics

blood types colourful

There are eight blood groups and they are classified using two systems - ABO System and Rhesus system. Your blood group is determined by the genes you inherit from your parents. 

ABO System

The ABO System 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 groups types compatibility

 

Irish Blood Group Type Frequency Distribution

Blood group O Positive is the most common group in Ireland while AB negative is the least common.

 

All blood groups are needed, and you don't need to know your blood type in order to give blood! After your first donation, we'll be able to tell you your blood type.