The 2011 Nobel Prize in Physiology or Medicine is announced. Bruce A. Beutler and Jules A. Hoffmann received one-half of the 2011 Nobel Prize in Physiology or Medicine, for their discoveries concerning the activation of innate immunity; the other half went to Ralph M. Steinman for his discovery of the dendritic cell and its role in adaptive immunity. Three winners' work has revolutionized our understanding of the immune system. And it has a bright prospect in the applied domain of anti-infections immunity, organ transplantation, and treatment of autoimmune diseases.