Photo from the Nobel Foundation archive.
The Nobel Prize in Physiology or Medicine 1930
Born: 14 June 1868, Vienna, Austrian Empire (now Austria)
Died: 26 June 1943, New York, NY, USA
Affiliation at the time of the award: Rockefeller Institute for Medical Research, New York, NY, USA
Prize motivation: "for his discovery of human blood groups."
Prize share: 1/1
When a person loses lots of blood through accident or illness, it must be replaced. When transfusions from one person to another were tried, however, the result was very often disastrous. Karl Landsteiner discovered why: when different people's blood was mixed, the blood cells sometimes clotted. He explained in 1901 that people have different types of blood cells, that is, there are different blood groups. The discovery led to blood transfusions between people with compatible blood groups.