Updated date:

The Rarest Blood Type in the ABO Blood System

Vials being filled with donor blood

Vials being filled with donor blood

Knowledge of the ABO and Rhesus blood systems is very important for human blood transfusions. Several other blood systems have been identified and these are also very important during pre-transfusion testing.

For blood transfusion to be successful, the donor’s blood must be compatible with the recipient. In blood banks and hospitals, supply problems are more frequent for rare blood types than they are for common blood types. In this article, to look at the rarest blood type, we will focus on the ABO and the Rh blood systems.

The letters A, B and O are used to denote blood types. + and - signs are used to denote the present and absence of the Rh factor. Here's more about the ABO blood-typing system.

What is the Rarest Blood Type?

The tables and figures below show the percentage of the world’s population with each blood type. Table 2 and figure 2 separate the information for Rh- and Rh+ while table 1 and figure 1 where produced without distinguishing between Rh- and Rh+.










The Rarest Blood Type (Not Stratified by Rhesus Factor)

Approximately 43.9%, 34.8%, 16.6% and 5.1% of the world’s population have blood groups O, A, B and AB respectively.

Figure 1. Approximate Distribution of ABO Blood Group Phenotypes to Identify the Rarest Blood Type

Figure 1. Approximate Distribution of ABO Blood Group Phenotypes to Identify the Rarest Blood Type

Without stratification (separating) by Rh factor, from table 1 and figure 1, you can clearly see that blood type AB has the lowest percentage (5.1%) with respect to other blood types in the ABO system.

AB is the rarest blood type if you pool both Rh+ and Rh- together. However, we are not going to stop here. The section below presents the percentages but this time they are shown by Rh- and Rh+ (separately).

The Rarest Blood Type Stratified by Rhesus factor

Presenting the data by Rh factor gives a more interesting result.

About 36.4%, 28.3%, 20.6%, 5.1%, 4.3%, 3.5%, 1.4% and 0.5% of the world’s population have blood groups O+, A+, B+, AB+, O-, A-, B- and AB- respectively. So, after stratification by Rh factor, you can clearly see that blood type AB- has the lowest frequency in the world.














Figure 2. Aproximate Distribution of ABO Blood Group and Rh factor (Phenotypes) to identify the rarest blood type

Figure 2. Aproximate Distribution of ABO Blood Group and Rh factor (Phenotypes) to identify the rarest blood type


You can say that among the ABO types, AB- is the rarest blood type in humans. However, the second most rare blood type is not AB+ (approx. 5.1%). In fact all the Rh-negative blood groups are rarer than the AB+ blood group. Therefore, in general we can also say that Rh- blood types are rarer than Rh+ blood types.

Data on the frequency distribution may change with time. Therefore, It is likely that newer data is available on the percentage of the population per ABO/Rh blood types.


Gale on March 05, 2020:

B- here

Waves on July 18, 2019:

Is it true that Maori(polynesian to New Zealand)have rare blood types ?

Allison on July 08, 2019:

B- here

saburouta on May 11, 2019:

Rh-NULL type blood is the actual rarest blood type. Why did you only include Rh+ and Rh-? There’s Rh null too. What sucks though, didn’t realize 0.5% was the amount of worldwide populace with AB-. That’s my type too. Incredible; I knew it was the rarest, but not that rare. No wonder it’s taking so long to get a new heart. They’re rare to get in the first place, but this does not give me hope lol. 10 years should be enough, I’d think.

esme walker on April 24, 2019:

type AB- :)

Pamela on April 22, 2019:

A+ with K antibodies

Mohammad W on January 09, 2019:

AB- ;)

Debbie on January 04, 2019:

RH- here

ted on December 08, 2018:

my blood type is


hassan on October 28, 2018:

B- here

Alex on October 25, 2018:

My blood type is A- and both my kids are A+ what is my husbands blood type ?

Collin on October 21, 2018:

I am A+

Joy on September 26, 2018:

AB rh D blood

Aleena Thompson on September 21, 2018:

I am ABO positive. I have no idea what that means

Lorraine on July 21, 2018:

I'm B-

IMTM on July 20, 2018:

I'm 0+

Hamza Dildar on July 05, 2018:

my blood group is B-

Brandan on May 30, 2018:

Im O+

Kristine on May 14, 2018:

I'm O-

Matthew on May 01, 2018:

About damn time I have a special trait I’m AB+

Stop. on April 07, 2018:

A+ for me.

Kryss on April 05, 2018:

I am B+

Nadeem on March 25, 2018:

i am O-negative

Martin on January 19, 2018:

I am A2B- :D

B on December 19, 2017:

Everyone who put AB- wanted to be in the rare percentage

Sun on May 26, 2017:

I am Ab + .when we had blood group test in class ,i was an ab and no other mates had that .i was so small and thought somethingbmust be wrong with me .

simul on August 30, 2014:

I am ab negative

Edmund Custers (author) on November 07, 2013:

It is great that you are helping those in need by donating blood. Thanks for stopping by. Have a great day!

DREAM ON on November 07, 2013:

Blood we all have it and we never think about it. Thanks for sharing. So now I have a bloody idea what different types there are and that reminds me it's time to give blood once again.I try to give as often as I can sometimes I forget. Have a good day.

Related Articles