Editing 1921 in science (section)

==Medicine==
* April–August – [[Nicolae Paulescu]] publishes papers on the preparation and therapeutic effects in animal subjects of an aqueous [[pancreatic]] extract.
* July 18 – The first [[Bacillus Calmette-Guérin|BCG]] vaccination against [[tuberculosis]].
* July 27 – Researchers at the [[University of Toronto]] led by [[biochemist]] [[Frederick Banting]] announce the discovery of the [[hormone]] [[insulin]].
* American biochemist [[Elmer McCollum]] identifies the presence of a component in [[cod liver oil]] which cures [[rickets]], which he calls [[vitamin D]].<ref>{{cite web|url=https://www.thestar.com/printarticle/239341|first=Suzanne|last=Carere|title=Age-old children's disease back in force|work=thestar.com|location=Toronto|date=2007-07-25|accessdate=2012-01-26|archive-url=https://web.archive.org/web/20080517044348/http://www.thestar.com/printArticle/239341|archive-date=2008-05-17|url-status=dead}}</ref>
* [[Fidel Pagés]] pioneers [[epidural anesthesia]].