Rh-Null Blood: The World's Rarest Blood Type - Facts & Information

Rh-null blood is the rarest blood group in the world. It is so rare that only about 43 people in the world are known to have it. Rh-null blood does not have any of the Rh antigens, which are proteins on the surface of red blood cells. This makes it very difficult for people with Rh-null blood to find compatible blood for transfusions.