Here is a look at this year's winners and their work:
Nobel Prize in physiology or medicine
Bruce Beutler of the U.S. and Frenchman Jules Hoffmann won the Nobel Prize in medicine for their discoveries concerning the activation of innate immunity.
Bruce Beutler and Jules Hoffmann discovered receptor proteins that can recognize such microorganisms and activate innate immunity, the first step in the body's immune response.
The discoveries that are awarded the 2011 Nobel Prize have provided novel insights into the activation and regulation of our immune system. They have made possible the development of new methods for preventing and treating disease, for instance with improved vaccines against infections and in attempts to stimulate the immune system to attack tumors. These discoveries also help us understand why the immune system can attack our own tissues, thus providing clues for novel treatment of inflammatory diseases.
Image: In this Nov 23, 2007 photo, Bruce Beutler, left, and Jules Hoffmann , right, receive the Balzan Prize in Bern, Switzerland.
Text& Images: AP