Most common - 37.4% of US donors
O-positive is the most common blood type in the United States and worldwide, found in approximately 37.4% of US donors. While not a universal donor (unlike O-negative), O-positive can donate red cells to all Rh-positive recipients - covering roughly 84% of the US population. This makes O-positive blood an enormous contributor to the blood supply.
Antigens present
Rh-D only (no A, no B antigens)
Antibodies produced
Anti-A, Anti-B
Antigens are proteins on the surface of red blood cells. Antibodies are produced by the immune system against antigens it does not carry. When incompatible blood is transfused, antibodies bind to foreign antigens and trigger a haemolytic reaction.
Select your blood type:
Can donate red cells to:
4 compatible types
Can receive red cells from:
2 compatible types
| Population | Frequency |
|---|---|
| US blood donors (Red Cross estimate) | 37.4% |
| Global population (estimate) | 38.3% |
O-positive is the single most common blood type globally, found in approximately 37.4% of US donors and 38.3% of the world population according to the American Red Cross and Stanford Blood Center. In many parts of sub-Saharan Africa, O-positive frequencies exceed 50%. Due to its high frequency, O-positive is usually plentiful in blood banks. However, demand is also high, so regular donation remains important.
Studies have found that O-type individuals (both O+ and O-) tend to have lower levels of von Willebrand factor and factor VIII compared to non-O types. This may modestly reduce the risk of venous thromboembolism (deep vein thrombosis, pulmonary embolism). Some large cohort studies have also suggested slightly lower risk of coronary artery disease in O-types, though findings are not fully consistent. These are population-level statistical associations, not individual diagnoses. O-positive individuals can safely donate blood every 56 days for whole blood, or every 112 days for Power Red double red cell donation.
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.
O-positive mothers are Rh-positive. Being Rh-positive means you will not develop anti-D antibodies, so Rh incompatibility is not a pregnancy concern for you. Your ABO type (O) also does not create pregnancy complications - ABO incompatibility between mother and fetus is usually mild and rarely requires intervention. If you are O-positive and pregnant, your blood type does not add any specific risk factors related to Rh or ABO blood group incompatibility.
Full Rh factor pregnancy guide +As an organ donor, O-positive donors can give organs to O-positive, A-positive, B-positive, and AB-positive recipients. As a recipient, O-positive patients can receive organs from O-positive or O-negative donors. This gives O-positive transplant recipients a reasonable compatible donor pool. HLA tissue typing and crossmatch testing are still required beyond ABO compatibility for all solid organ transplants.
ABO compatibility for organ transplant follows the same rules as transfusion - O+ can donate organs to: O+, A+, B+, 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 +O-type plasma (both O+ and O-) contains both anti-A and anti-B antibodies, making it the most restricted plasma type. O plasma can only be given to O recipients. For plasma donation purposes, AB-type donors are preferred because AB plasma is universally compatible. If you are O-positive, your most impactful donation is whole blood or double red cell donation rather than 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 +