what are the blood types in order of rarity
- 1 AB Negative is the rarest blood type, and less than a percent of the world's population has this rare blood. 2  There will be slight differences in the rarity of blood types depending on location and country, but generally, this blood type is not seen very often.3  B Negative. B Negative is the second rarest type of blood in the world. 2  O Negative. 3  Also very rare, O Negative blood is seen in only in a few people. 4  But unlike other rare blood types, O Negative can be used for red blood cell donations to almost any other blood type in existence.