Britannica Sources used in this answer

Which blood type is most common around the world?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Close-up illustration of multiple human red blood cells with their characteristic disc shape, floating against a red background. — blood group The major component of human blood is the red blood cell.

Blood group O is the most common blood type throughout the world.1

While blood type frequencies vary across different populations due to factors like genetic drift and natural selection, type O is particularly prevalent among the peoples of South and Central America. In contrast, other blood types show distinct regional patterns: for example, type B is more common in parts of Asia, such as northern India, while type A reaches its highest frequency among specific groups like the Australian Aboriginal peoples, the Blackfoot Indians of Montana, and the Sami people of northern Scandinavia.12