Ion Cantacuzino (also known as Ioan Cantacuzino, born November 25, 1863, Bucharest - January 14, 1934, Bucharest) was a Romanian physician and microbiologist, founder of the Romanian School of Immunology and Experimental Pathology. He was a university professor and a member of the Romanian Academy.
Based on his research on the cholera vibration, Cantacuzino developed a method of vaccination against alcohol, called the "Cantacuzino method", a method used today in countries where there are still cases of cholera.
Founder of the Institute of Serums and Vaccines and the Laboratory of Experimental Medicine of the Medical Faculty of Bucharest.

Ion Cantacuzino has been a full member of the Romanian Academy since 1925, a member of the Hygiene Committee of the League of Nations, of the societies of Biology, of Exotic Pathology and of the Paris Academy of Sciences. Many universities have awarded him the title of Doctor honoris causa, Lyon (1922), Brussels (1924), Montpellier (1930), Athens (1932) and Bordeaux (1934).