The rarest blood type in humans is the "golden blood" type, also called Rh null blood. This extraordinary blood type lacks all Rh antigens on red blood cells and is extremely rare, with fewer than 50 known cases worldwide. It is so rare that it has been found in only about 43 to 48 people ever reported. This blood type is especially precious for transfusion medicine because it can be donated to anyone with rare blood types within the Rh system, but people with Rh null blood can only receive blood from others with the same type.
Other notably rare blood types include AB-negative among the main ABO and Rh types, but Rh null far surpasses it in rarity.
