Which is the 3 rarest blood group?

The Three Rarest Blood Types in the World

While most people fall into one of the eight common blood types, a few are far rarer—and far more mysterious. Among them, one stands out as the rarest of all: Rh-null, often called “golden blood.” With fewer than 50 confirmed cases worldwide, this blood type lacks all Rh antigens, making it a universal donor for anyone with rare Rh deficiencies. But it’s also incredibly fragile to match, and storing or transfusing it poses serious challenges.

Another rare type is AB−. Though AB is the rarest of the ABO groups, AB− is particularly scarce because of the negative Rh factor. It’s found in less than 1% of the global population, mostly among people of European descent. While not as rare as Rh-null, AB− blood is still in constant demand, especially for plasma transfusions, since AB− individuals can receive red cells from almost any blood type but can only donate to other AB patients.

Then there’s the Bombay blood type—also known as the HH phenotype. First identified in Mumbai (formerly Bombay), this blood type doesn’t express the H antigen, the foundation for A and B antigens. As a result, people with this type can only receive blood from other Bombay donors, even if their ABO type appears compatible. It’s almost exclusively found in South Asia, particularly in India, and is so rare that many hospitals don’t routinely test for it.

These rare blood types remind us how diverse human biology can be. While they present medical challenges, they also highlight the importance of specialized blood registries and global cooperation in saving lives—one rare drop at a time.