Blood groups (A, B, AB, and O) are inherited. The presence or absence of an Rh factor on the red blood cells is what makes your blood type positive or negative. Blood groups (A, B and O) and Rh types are descriptions of certain antigens found on red cells. People with type A blood have A antigens on their red blood cells and lack B antigens; people with type B blood have B antigens and lack A antigens; people with type AB blood have both antigens, and people with type O blood lack both A and B antigens.

In addition, blood is typed as either Rh-positive or Rh-negative, referring to the presence or absence of the Rh antigen, which is named for the fact that it was first discovered in the Rhesus monkey. Most people (about 85 percent) are Rh-positive, and that figure is even higher for African-Americans and Asians.

Who Can Receive Whose Red Blood Cells:

O negative can use O negative only

O positive can use O positive or O negative

A negative can use A negative or O negative

A positive can use A positive, A negative, O positive or O negative

B negative can use B negative or O negative

B positive can use B positive, B negative, O positive or O negative

AB negative can use AB negative, A negative, B negative or O negative

AB positive can use All Blood Types

Notice that all blood types can receive O negative red blood cells. This is why O negative is used in emergencies when there is no time to determine the blood type of the patient. This is also why donors who are O negative are always in high demand

Blood Type Inheritance

It’s inherited...

Whether your blood type is A, B, AB or O, is based on the blood types of your mother and father.