The most celebrated medical discovery of this century is comprised of two distinct stages: (1) that of fundamental research, i.e. the experimental demonstration of the presence in the pancreas of an antidiabetic hormone done by Paulescu and published on 31 August 1921 in the Archives Internationales de Physiologie; and (2) the clinical application of the discovery of insulin in the treatment of diabetes in man, the stage completed in 1922 by the Canadian group comprised of Collip, Macleod, Banting and Best.