There are 8 main blood types most people talk about, but in reality there are hundreds of recognized blood types when all blood group systems are included.

Quick Scoop

  • In everyday medicine, blood is usually grouped into eight common types: A+, A-, B+, B-, AB+, AB-, O+, O-.
  • These 8 come from combining the ABO system (A, B, AB, O) with the Rh factor (positive or negative).
  • Scientists have identified over 300 different blood group antigens , organized into around 47 blood group systems as of 2024, which means there are potentially hundreds of distinct blood types in a strict scientific sense.

Everyday vs scientific answer

  • Everyday answer (hospital / donor cards): “There are 8 blood types” – this is what matters for most transfusions and what you see on donation posters.
  • Scientific answer: The International Society of Blood Transfusion recognizes 47 blood group systems and 350+ known red‑cell antigens, so the number of possible unique blood types is in the hundreds (and still growing as new variants are discovered).

Why people say “8” blood types

  • The ABO and Rh systems are the ones that most strongly affect transfusion safety, so labs routinely match only these for standard cases.
  • For special cases (rare blood, multiple transfusions, certain diseases), doctors may look at additional blood groups to find a more precise match.

Rare and “special” blood types

  • Beyond A/B/O/Rh, there are systems like MNS, Duffy, Kidd, and others; unusual combinations in these can produce very rare blood types.
  • Examples include the Bombay phenotype , certain Kidd‑null and McLeod types, which require specially matched donors because standard “compatible” blood can be dangerous for them.

Can new blood types appear?

  • New blood types are identified when researchers find a new antigen or a new way an antigen is built on red blood cells.
  • As genetic variants continue to be discovered worldwide, the catalog of recognized blood types keeps expanding over time.

Information gathered from public forums or data available on the internet and portrayed here.