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Health Sciences Authority

Rhesus negative blood

Find out more about this blood group which is considered rare.

Last updated 13 March 2026

Only about 1.5% of our donor population are Rh negative. Rh negative blood is found most commonly in Caucasians and Indians.

Patients with Rh negative blood group, requiring a blood transfusion, are recommended to receive Rh negative blood.

Group O Rh negative blood is recommended for the emergency transfusion of females with current or future child-bearing potential before their blood groups can be tested, if they have a higher likelihood of being Rh negative.

Hence, it is crucial to maintain a sufficient blood stock of Rh negative blood.

If you have Rh negative blood, please donate regularly (at least twice a year) to help maintain our blood stocks and save lives.

What is Rh negative blood?

The Rh (“Rhesus”) blood group antigen (D antigen) is a protein found on the surface of red blood cells. People who have the antigen on the surface of their red blood cells have Rh positive blood such as A+, B+, O+ and AB+.

Rh negative blood such as A-, B-, O- and AB-, does not have the (D) antigen on the surface of the red blood cells.

Why it is crucial to maintain a sufficient blood stock

Patients with Rh negative blood group are recommended to receive Rh negative blood. This is because Rh positive blood increases their risks of developing antibodies to the Rh antigen, which may lead to increased breakdown of the transfused blood and adverse transfusion reactions. This can be potentially life-threatening.

Group O Rh negative blood is recommended for the emergency transfusion of females with current or future child-bearing potential before their blood groups can be tested, if they have a higher likelihood of being Rh negative.

This is to prevent them from developing antibodies to the Rh antigen, which can lead to potentially serious pregnancy complications in the future.

Hence, it is crucial to maintain a sufficient blood stock of Rh negative blood.

The challenges of maintaining a sufficient blood stock

Ideally, we need to maintain a 12-day stockpile for Rh negative blood to respond to civil or medical emergencies in Singapore.

Any sudden increase in the Rh negative blood usage, for instance, when a patient with a specific Rh negative blood group suffers a massive blood loss due to surgery, can cause the Rh negative blood stock to drop.

Rh negative blood stock may also dip during festive seasons and long holiday periods. When this happens, it is more difficult for the blood stock to recover as the proportion of donors with Rh negative blood is very small.

How you can help

If you have Rh negative blood, please donate regularly (at least twice a year) to help maintain our blood stocks and save lives. We encourage everyone who is healthy to make an appointment to donate blood, regardless of your blood group.