Physiology or medicine was the third prize category Alfred Nobel mentioned in his will. Nobel had an active interest in medical research. He came into contact with Swedish physiologist Jöns Johansson through Karolinska Institutet around 1890. Johansson worked for a brief period in Nobel's laboratory in Sevran, France during the same year. The Nobel Prize in Physiology or Medicine is awarded by the Nobel Assembly at Karolinska Institutet. This volume is a collection of the Nobel lectures delivered by the Nobel laureates, together with their biographies and the presentation speeches for the period 2011–2015. List of laureates and their award citations:(2011) Bruce A Beutler and Jules A Hoffmann "for their discoveries concerning the activation of innate immunity", and Ralph M Steinman "for his discovery of the dendritic cell and its role in adaptive immunity";(2012) Sir John B Gurdon and Shinya Yamanaka "for the discovery that mature cells can be reprogrammed to become pluripotent";(2013) James E Rothman, Randy W Schekman and Thomas C Südhof "for their discoveries of machinery regulating vesicle traffic, a major transport system in our cells";(2014) John O'Keefe, May-Britt Moser and Edvard I Moser "for their discoveries of cells that constitute a positioning system in the brain";(2015) William C Campbell and Satoshi Ōmura "for their discoveries concerning a novel therapy against infections caused by roundworm parasites", and Tu Youyou "for her discoveries concerning a novel therapy against Malaria".