Blood Types — Stanford Blood Center

As you probably know, we all have a blood type. But do you know what makes each type unique?

While several blood group systems are used to type your blood, ABO is the most important. Your ABO type is based on the presence or absence of two antigens (A and B) on the surface of red blood cells. There are four ABO types: A, B, AB and O.

Your blood type is also determined by Rh status: Rh+ or Rh-. That leaves us with eight possible blood types:

A+
A-

B+
B-

AB+
AB-

O+
O-

Each of these eight types is unique. Blood types determine who you can give blood to and receive blood from. Which type of donation is best for you is determined by your blood type, as well as patient need. Read more to find out what makes your blood type special: