A-

A- Blood Type

Less common - 6.3% of US donors

A-negative blood carries the A antigen but lacks the Rh-D antigen. This makes A-negative donors especially valuable: they can donate to A-positive, A-negative, AB-positive, and AB-negative recipients - covering all four A-type and AB-type individuals. Like O-negative, A-negative blood is safe for Rh-negative recipients, which widens its usefulness considerably.

Can donate red cells to:

A+A-AB+AB-

4 compatible types

Can receive red cells from:

A-O-

2 compatible types

UK figures

A negative in the UK: 8% of donors, and the group NHSBT calls the universal platelet type

A negative accounts for 8% of NHS Blood and Transplant donors in the UK, against 6.3% of US donors. NHSBT describes A negative as "the universal platelet type", which is why the service recruits A negative donors specifically for platelet donation as well as whole blood. For red cells the rule is the same in both countries and is set by biology rather than by the blood service: A negative red cells can go to A+, A-, AB+ and AB- patients, and an A negative patient can receive red cells only from A negative or O negative donors. NHSBT also publishes that 77% of its donors are Rh D positive.

Source: NHS Blood and Transplant, Blood types (blood.co.uk/why-give-blood/blood-types/). NHSBT states its donor percentages are accurate at February 2026 and rounded to the nearest whole number. Figures checked 7 September 2026. US percentage from the American Red Cross figures used elsewhere on this site.

What Is A- Blood?

Antigens present

A antigen only (no B, no Rh-D)

Antibodies produced

Anti-B (anti-D only if sensitised)

Antigens are proteins on the surface of red blood cells. The ABO antibodies (anti-A and anti-B) are naturally occurring - present from infancy against whichever A or B antigen you lack. The Rh anti-D antibody is different: Rh-negative people do not carry it from birth and only form it after exposure to Rh-positive blood through transfusion or pregnancy (sensitisation), which is why anti-D immunoglobulin is given to prevent it. When incompatible blood is transfused, antibodies bind to foreign antigens and trigger a haemolytic reaction.

Interactive Compatibility Tool

Select your blood type:

A-Less common - 6.3% of US donors

Can donate red cells to:

A+A-AB+AB-

4 compatible types

Can receive red cells from:

A-O-

2 compatible types

Full A- guide

How Rare Is A-?

Population	Frequency
US blood donors (Red Cross estimate)	6.3%
Global population (estimate)	6.1%

A-negative is found in approximately 6.3% of US donors and 6.1% of the global population. It is relatively uncommon, which makes each A-negative donor valuable to the blood supply. A-negative is more common in Europe, particularly in Nordic and Celtic populations, and less common in East Asian and African populations.

Clinical Notes for A-

A-negative individuals share the same ABO-related epidemiological associations as A-positive (modest A-type epidemiological patterns). The Rh-negative status means they lack the Rh-D antigen, which is generally clinically neutral in everyday life. There are no known health disadvantages to being Rh-negative. A-negative people can donate whole blood every 56 days. Platelets from A-negative donors are particularly useful in paediatric and cancer care.

Note: Associations between blood type and disease risk are from observational studies and are not deterministic. They do not change your clinical management. Cite any specific associations with your clinician.

Pregnancy Implications for A-

A-negative mothers are Rh-negative. If you are A-negative and the father of your baby is Rh-positive, there is a chance your baby will be Rh-positive. This creates the risk of Rh sensitisation - where your immune system produces anti-D antibodies that could, in a future pregnancy, cross the placenta and attack fetal red cells. Anti-D immunoglobulin (RhoGAM) is routinely offered to Rh-negative mothers at around 28 weeks and within 72 hours of delivery. This prophylaxis is highly effective. Ensure your obstetrician records your blood type at your first antenatal appointment.

Full Rh factor pregnancy guide +

Organ Transplant Compatibility for A-

A-negative organ donors can give to A+, A-, AB+, and AB- recipients. As an A-negative recipient, you can only receive organs from A-negative or O-negative donors - a smaller pool that may mean longer waiting times on transplant lists. Paired kidney exchange programs can help bridge ABO and Rh incompatibilities in living-donor situations. HLA tissue matching and crossmatch testing are required in addition to ABO compatibility.

ABO compatibility for organ transplant follows the same rules as transfusion - A- can donate organs to: A+, A-, AB+, AB-. However, HLA tissue matching and crossmatch testing are also required, and sensitisation from prior transfusions or pregnancies can restrict compatibility further.

Full organ transplant guide +

Plasma Donation for A-

A-type plasma (both A+ and A-) contains anti-B antibodies and can be given to A or O recipients. The Rh factor is not relevant for plasma compatibility. If you are A-negative, consider whole blood or red cell donation as your primary contribution, as your red cells are more uniquely valuable than your plasma.

Note: Plasma compatibility rules are the inverse of red-cell rules because plasma carries antibodies, not antigens. AB plasma is the universal plasma donor.

Plasma compatibility chart +

Frequently Asked Questions about A-

What percentage of UK blood donors are A negative?

8% of NHS Blood and Transplant donors in the UK are A negative, on NHSBT figures accurate at February 2026. That is higher than the 6.3% recorded among US donors. NHSBT describes A negative as the universal platelet type and recruits A negative donors for platelet donation as well as whole blood.

Who can A-negative donate blood to?

A-negative can donate red cells to A+, A-, AB+, and AB- recipients. These four types can all receive A antigens without a reaction, and because A-negative blood lacks the Rh-D antigen, it is safe for both Rh-positive and Rh-negative recipients.

Who can A-negative receive blood from?

A-negative can only receive red cells from A-negative or O-negative donors. A-negative people carry naturally-occurring anti-B antibodies (ruling out B and AB types), and being Rh-negative they would form anti-D antibodies if given Rh-positive blood, so all Rh-positive types are avoided.

Is A-negative a rare blood type?

A-negative is not extremely rare, but it is less common than A-positive or O-positive. At 6.3% of US donors, it sits in the 'less common' category alongside O-negative. Blood banks sometimes face shortages of A-negative because demand from both A-negative and AB-negative patients must be met from a limited pool.

What happens if A-negative person receives A-positive blood?

If an A-negative person - particularly a woman of childbearing age or anyone who may need future transfusions - receives Rh-positive blood, their immune system may develop anti-D antibodies (Rh sensitisation). This is usually avoided in practice: blood banks always try to give Rh-compatible blood. In a life-threatening emergency, Rh-positive blood may sometimes be used when Rh-negative is unavailable, with careful monitoring.

Can two A-negative parents have an A-positive child?

No. If both parents are Rh-negative (genotype dd), they cannot pass a D allele to their child. All children of two Rh-negative parents will be Rh-negative. Two A-negative parents can have children who are A-negative or O-negative, depending on whether each parent carries one or two A alleles.

Related Blood Types

A+O-AB-AB+