Among the eight major blood types, AB negative is the rarest, found in roughly 1% of the global population. But if you expand beyond the standard ABO system, far rarer types exist. Fewer than 50 people worldwide have ever been identified with Rh-null blood, sometimes called “golden blood,” making it the rarest known blood type on Earth.
AB Negative: The Rarest Common Type
Blood typing sorts people by two systems: ABO (which determines whether you’re A, B, AB, or O) and Rh factor (positive or negative). Combining these gives the eight familiar blood types. According to NHS Blood and Transplant data, the distribution looks like this:
- O positive: 36%
- A positive: 28%
- O negative: 14%
- A negative: 8%
- B positive: 8%
- B negative: 3%
- AB positive: 2%
- AB negative: 1%
AB negative is rare because it requires inheriting an A gene from one parent and a B gene from the other (already uncommon), plus inheriting the Rh-negative trait from both parents. Each requirement narrows the odds. In the U.S., the numbers shift further by ethnicity. American Red Cross data shows AB negative occurs in just 0.1% of Asian American donors and 0.2% of Latin American donors, compared to about 1% of white donors.
Golden Blood: Fewer Than 50 People Worldwide
Beyond the standard eight types, there are hundreds of blood group antigens, and some combinations are extraordinarily rare. The rarest of all is Rh-null, nicknamed “golden blood.” A person with Rh-null blood is missing all 61 antigens in the Rh blood group system, not just the D antigen that determines positive or negative status. About 43 people have ever been reported to have it.
Rh-null blood is caused by genetic mutations that prevent the body from producing any Rh proteins on the surface of red blood cells. Because it lacks every Rh antigen, it can theoretically be transfused to anyone with a rare Rh blood type without triggering an immune reaction. That universal compatibility for Rh-rare patients is what earned it the “golden” label. The flip side is brutal for the people who have it: if they ever need a transfusion themselves, they can only receive Rh-null blood from one of the handful of other people on the planet who share their type.
The Bombay Phenotype
Another exceptionally rare type is the Bombay phenotype, known in medical shorthand as Oh. People with this blood lack the H antigen, a precursor molecule that sits on red blood cells and serves as the foundation for A and B antigens. Without H antigen, neither A nor B can be built, so Bombay blood looks like type O on a standard test. But it is not type O. People with this phenotype will have a severe transfusion reaction if given regular O blood, because their immune system recognizes even the H antigen as foreign.
The Bombay phenotype occurs in roughly 0.01% of the population in parts of Mumbai, where it was first discovered, and drops to about 0.0001% in European populations. Like Rh-null individuals, people with the Bombay phenotype can only safely receive blood from other Bombay donors.
Rare Types Vary by Ethnicity
Rarity is not the same everywhere. Blood type frequencies reflect ancestry, so a type that’s scarce in one population may be slightly more common in another. This goes well beyond ABO. The American Red Cross identifies several rare blood types that cluster in specific ethnic groups:
- U-negative and Duffy-negative: most common among African Americans
- RzRz: most common among Native American and Alaska Native populations
- Jk-null: most common among Pacific Islander and Asian populations
- Diego B-negative: most common among Hispanic populations
- Kell B-negative and Vel-negative: most common among white populations
This is why the Red Cross notes that the best transfusion matches for people with rare blood types often come from donors of the same racial or ethnic background. The genetic variants that produce these rare antigen profiles are inherited, and they tend to be shared within communities that share ancestry.
Why Rare Blood Creates Real Medical Challenges
For most people, blood type is a trivia question. For those with a rare phenotype, it can become a life-or-death logistics problem. Hospitals first need to identify that someone has a rare type, which requires specialized antibody testing that many labs aren’t equipped to perform. Once the need is confirmed, finding a compatible donor may require searching regional, national, or international databases.
Some blood services maintain frozen banks of rare red blood cell units. Frozen blood can be stored for years, even decades, but managing that inventory is complex. Donor screening criteria and testing methods evolve over time, which means stored units need periodic review to confirm they still meet safety standards. The International Society of Blood Transfusion operates the International Rare Donor Panel, a global coordination network that helps match patients with compatible donors across borders. A rare phenotype more readily available in one region of the world may be nearly impossible to find in another, so international collaboration fills gaps that no single country can cover alone.
For the small number of people with types like Rh-null or Bombay, donating blood when healthy is not just generous but practically essential. Their own future medical care may depend on a stored supply or on the willingness of a few dozen others scattered around the world to donate when the call comes.