Blood types are a classification of blood based on the antigens present in red blood cells. In the United States, O-positive is the most common blood type, and AB-negative is the rarest.

A blood transfusion is a procedure that restores blood to the body. It is essential that people undergoing the procedure receive the correct blood type, or it will trigger the immune system, causing sickness and complications.

According to the American Red Cross, roughly every 2 seconds, a person in the United States requires a blood transfusion. They also note that this procedure saves 4.5 million lives each year.

In this article, we discuss the rarest and most common blood types by ethnicity.

bags of blood which may contain any of the the most common blood type by raceShare on Pinterest
A person’s blood type may fall into any of the 36 human blood groups. Getty Images

People can define blood types using the ABO and Rhesus (Rh) blood group systems. These define blood types according to which antigens are present on red blood cells.

ABO system

This system classifies blood types as follows:

  • Blood group A has A antigens on the red blood cells.
  • Blood group B has B antigens.
  • Blood group O has neither A nor B antigens.
  • Blood group AB has both A and B antigens.

Rh system

Red blood cells may have another antigen called the Rh antigen on their surface. If it is present, the blood group is Rh-positive, but if it is absent, the blood group is Rh-negative.

Combining these two characteristics yields the eight most common blood types. Most people have one of these types:

  • O-positive
  • O-negative
  • A-positive
  • A-negative
  • B-positive
  • B-negative
  • AB-positive
  • AB-negative

The genes that a person inherits from their parents determine the mix of antigens and proteins in their blood.

These genetic factors tend to run in ethnic groups. As such, the American Red Cross suggests that when people, especially those with rare blood types, need blood, the best matches tend to come from people of the same race or ethnic background.

For this reason, some blood centers collect ethnic information from blood donors.

For some conditions, such as thalassemia and sickle cell disease, this matching is even more important because these conditions are more common among certain ethnic communities, and people may need frequent transfusions.

For example, only 2% of donors have a rare subtype of blood that doctors often use to treat sickle cell disease, but demand for it is increasing by 10–15% each year. The rarity of, and demand for, this type of blood emphasizes the importance of blood donors.

Click here to learn more about blood types.

In the U.S., 38% of the population has O-positive blood, making it the most common blood type.

According to the American Red Cross, the following statistics show the most common blood types in the U.S. based on the donor population:

  • African American: 47% O-positive, 24% A-positive, and 18% B-positive
  • Latin American: 53% O-positive, 29% A-positive, and 9% B-positive
  • Asian: 39% O-positive, 27% A-positive, and 25% B-positive
  • Caucasian: 37% O-positive, 33% A-positive, and 9% B-positive

The least common blood type in the U.S. is AB-negative, with less than 1% of the population having this type.

Statistics from the American Red Cross show that the following are the most rare forms of the major eight blood types in the U.S. based on the donor population:

  • African American: 0.3% AB-negative, 1% B-negative, and 2% A-negative
  • Latin American: 0.2% AB-negative, 1% B-negative, and 2% both A-negative and AB-positive
  • Asian: 0.1% AB-negative, 0.4% B-negative, and 0.5% A-negative
  • Caucasian: 1% AB-negative, 2% B-negative, and 3% AB-positive

A and B antigens only represent two of approximately 600 other known antigens that can differentiate blood types. It is important to make a distinction between the rarest of the eight most common blood types and the extremely rare subtypes.

Having an antigen that most people do not have, or missing an antigen that most people do have, means that an individual has a rare blood type.

According to the International Society of Blood Transfusion, if only 1 in 500 people are missing the same antigen as an individual, their blood type is rare. If only 1 in 1,000 people lack it, the individual’s blood type is very rare.

In addition, scientists have identified 36 different blood group systems, some of which can cause problems with blood transfusions.

Some of these rare blood types and blood group systems are distinctly more common in certain ethnic groups. The American Red Cross data below list the rare blood type and the ethnic group in which it is most common:

  • African American: U-negative and Duffy-negative blood types
  • Native American and Alaskan native: RzRz blood type
  • Pacific Island and Asian: JKnull blood type
  • Hispanic: Diego B-negative blood type
  • East European and Russian Jewish: Drori A-negative blood type
  • Caucasian: Kell B-negative and Vel-negative blood types

Experts base blood types on the different antigens and proteins present on red blood cells. To make sure that a transfusion supports an individual’s health instead of causing harm, there must be a good match between the donor’s blood type and that of the recipient.

As an individual’s genetic background influences their blood type, looking at the most common blood type by race or ethnicity can help healthcare professionals acquire and effectively use the most suitable blood and blood products for individuals requiring blood transfusions.