The essentials

Of the eight common blood types, AB negative is the rarest in the United States: about 6 people in 1,000. O positive and A positive are the most common. The ranking changes between populations, because blood types are inherited. Truly rare types, such as Rh null ("golden blood") or Bombay, lack an antigen almost everyone carries, which makes compatible blood very hard to find.

What is the rarest blood type?

The answer depends on which list you look at. Among the eight types printed on a standard report, AB negative comes last: 0.6% of the US population, followed by B negative at 1.5%[1]. In UK donors, AB negative is also the least common of the eight, at about 1%[3][4].

Blood banks use a stricter definition: your blood is rare if you lack an antigen that 99% of people carry, and extremely rare if 99.99% carry it[2]. By that measure, AB negative is not rare at all. The rarest known type is Rh null, with about 43 people ever reported worldwide[8].

ABO and Rh are only two of the 49 blood group systems recognized by the International Society of Blood Transfusion, which together hold about 400 antigens[6]. A routine blood type test reads only a few of them[11].

How do I read the blood type line on my report?

A fictitious result for a person with one of the least common of the eight types:

Fictitious example of a blood bank report (United States format)
TestResultPossible resultsFlag
ABO groupABA, B, AB or O-
Rh(D) typeNegativePositive or negative-
Blood type (summary)AB Rh negative (AB-)One of 8 types-
Antibody screenNegativeNegative or positive-
  1. ABO group AB: your red cells carry both the A and the B antigens. The lab checks it on the cells and again on the liquid part of the blood (back typing)[11].
  2. Rh(D) negative: your cells lack the RhD protein. In a transfusion, you should receive Rh-negative red cells[11].
  3. AB-: the combination of both lines. Uncommon, but not a health problem: there is no "high" or "low" here, so no flag is printed.
  4. Antibody screen negative: no unexpected antibodies against other red cell antigens were found today. This is the test that can reveal a rare type, because people who lack a common antigen may make antibodies against it after a transfusion or a pregnancy[7].

Have a blood bank report or a full set of lab results you are unsure about? BloodSense explains every line in plain words, so you know what to ask at your next visit.

Explain my lab report

Why does rarity matter for transfusion?

For most patients, the eight common types are enough. Type O blood can be given to people of any ABO group, people with type AB can receive A, B, AB and O, and Rh-negative patients should receive Rh-negative blood[11]. AB-negative donors are universal plasma donors: anyone can receive their plasma[1].

Rarity matters most for patients who need blood again and again, as in sickle cell disease or thalassemia. They do best with blood matched beyond ABO and Rh[4]. In England, a subtype called Ro is vital for sickle cell care, yet only 3% of regular donors have it[4].

How common is each blood type?

There is no single "normal" share: it depends on the population.

Share of each blood type in three populations (source in each column heading)
Blood typeUnited States, population[1]England, blood donors (February 2026)[3]China, 3.8 million adults[5]
O positive37.4%36%30.1%
O negative6.6%14%0.3%
A positive35.7%28%30.2%
A negative6.3%8%0.4%
B positive8.5%8%29.1%
B negative1.5%3%0.3%
AB positive3.4%2%9.6%
AB negative0.6%1%0.1%

The English figures describe donors, not the whole population, and are rounded[3]. In China, type B is almost as common as A or O, and Rh-negative blood of any kind is found in only about 1% of people[5].

Why does the rarest type change from country to country?

Blood types are inherited, so people who share ancestry tend to share blood types[2][4]:

  • In the United States, about 45% of White people have type O, against 51% of Black people and 57% of Hispanic people[2].
  • Rh-negative blood has been reported in 17.3% of White non-Hispanic US donors but in 1.7% of Asian US donors[5].
  • Within China itself, the Rh-negative share ranges from 0.3% in Mongolian people to 3.3% in Uygur people[5].
  • The Ro subtype is about 10 times more common in people of Black heritage than in other donors in England[4].

This is why blood services recruit donors from every background: a close match is most often found in someone of similar ancestry[4].

Which blood types are truly rare?

  • Common A less frequent standard type. AB negative, B negative or O negative: uncommon, but stocked by blood banks[4].
  • Possible An uncommon subtype. Ro, or a missing antigen from another system, matters mainly for people who need many transfusions[4].
  • Rare Bombay type. The red cells lack the H antigen, so a routine test can read them as type O. People with this type can only safely receive Bombay blood. It is found mostly in western and southern India: one hospital in Puducherry found 3 cases in 35,497 people tested[9].
  • Rare Rh null. All Rh antigens are missing. It often causes a mild, lasting breakdown of red cells (hemolytic anemia). Once antibodies form, only Rh null blood is safe, from relatives, frozen stocks or rare donor registries[7][8].

Because no single country holds enough of these types, national programs share donor data through the WHO International Rare Donor Panel, and units can be sent abroad when a patient needs them[10][4].

What does my blood type change for pregnancy?

If you are Rh negative and your baby is Rh positive, your body can make antibodies against the baby's red cells. In a later pregnancy, these antibodies can destroy the baby's red cells and cause high bilirubin and jaundice. Injections of Rh immune globulin, now used routinely in prenatal care, have made this problem much less common[12]. For women with Rh null or another very rare type, care is planned early with a specialist blood bank[7].

How can I find out my blood type, and whether it is rare?

  • Check your records: blood typing is part of prenatal care and is done before a transfusion or a transplant[11][12].
  • Ask your doctor for an ABO and Rh typing. It is a simple blood draw and needs no special preparation[11].
  • Give blood. Donors are told their blood type, and blood services test donations further and tell donors when their blood is rare[2][4].
  • Keep any letter or card that mentions a rare type or a red cell antibody, and show it before surgery or a transfusion.
  • Tell the hospital about past transfusions, pregnancies and any bone marrow or stem cell transplant, since these can change what the blood bank needs to test.
  • Remember that the routine test skips most minor antigens[11].

When should I see a doctor?

When to see a doctor

  • Emergency: call 911 for heavy bleeding, fainting, severe shortness of breath, or fever, chills, back pain or dark urine during or soon after a transfusion.
  • Within 24 to 48 hours if you are Rh negative and pregnant and have vaginal bleeding, a fall or a blow to the belly, or if you were told you have a rare type and surgery is being planned.
  • At your next appointment to confirm your blood type or discuss a positive antibody screen.

Questions to ask your doctor

  1. Has my blood type been confirmed by two separate samples?
  2. Was an antibody screen done, and what did it show?
  3. Do I need Rh immune globulin during this pregnancy?
  4. If I need surgery, should the blood bank prepare blood in advance?
  5. Would my blood be useful to a rare donor program?

Frequently asked questions

Is AB positive a rare blood type?

It is uncommon but not rare in the blood bank sense: 3.4% of people in the United States have it. People with AB positive can receive red cells of any type[1].

Is O negative the rarest blood type?

No. About 7% of people are O negative[2]. It feels scarce because hospitals use it so often in emergencies, when there is no time to test the patient's type[2][4].

Why is Rh null called "golden blood"?

The name is a popular way of saying how rare it is. It does not mean the blood is purer or safer for everyone[8].

Does a rare blood type affect my health?

The eight standard types do not cause illness. Rh null is an exception: it is often linked to a mild, chronic breakdown of red cells, which a complete blood count and a reticulocyte count can follow[7].

  1. Stanford Blood Center. Blood types. stanfordbloodcenter.org (accessed October 25, 2026)
  2. American Red Cross. Blood types explained: A, B, AB and O. redcrossblood.org (accessed October 25, 2026)
  3. NHS Blood and Transplant. Blood types (data accurate at February 2026). blood.co.uk (accessed October 25, 2026)
  4. NHS Blood and Transplant. Rare blood types. blood.co.uk (accessed October 25, 2026)
  5. Liu J, Zhang S, Wang Q, Shen H, Zhang Y, Liu M. Frequencies and ethnic distribution of ABO and RhD blood groups in China: a population-based cross-sectional study. BMJ Open. 2017;7(12):e018476. doi:10.1136/bmjopen-2017-018476 (accessed October 25, 2026)
  6. International Society of Blood Transfusion. Red Cell Immunogenetics and Blood Group Terminology Working Party (registry updated September 24, 2026). isbtweb.org (accessed October 25, 2026)
  7. Shahverdi E, Moghaddam M. Rhnull phenotype: molecular basis, serologic features, clinical manifestations, and transfusion challenges. A scoping review of published cases. Immunohematology. 2026;42(2):42-47. doi:10.2478/immunohematology-2026-008 (accessed October 25, 2026)
  8. Cleveland Clinic Health Essentials. What is "golden blood"? And why is it so rare? health.clevelandclinic.org (accessed October 25, 2026)
  9. Mallick S, Kotasthane DS, Chowdhury PS, Sarkar S. Bombay blood group: is prevalence decreasing with urbanization and the decreasing rate of consanguineous marriage. Asian J Transfus Sci. 2015;9(2):129-132. doi:10.4103/0973-6247.162695 (accessed October 25, 2026)
  10. Nance S, Scharberg EA, Thornton N, Yahalom V, Sareneva I, Lomas-Francis C. International rare donor panels: a review. Vox Sang. 2016;110(3):209-218. doi:10.1111/vox.12357 (accessed October 25, 2026)
  11. MedlinePlus Medical Encyclopedia. Blood typing. Reviewed January 29, 2026. US National Library of Medicine. medlineplus.gov (accessed October 25, 2026)
  12. MedlinePlus Medical Encyclopedia. Rh incompatibility. US National Library of Medicine. medlineplus.gov (accessed October 25, 2026)

This page is general information. It does not replace the advice of a doctor or a blood bank, who interpret your blood type with your history, pregnancies and past transfusions.