The eminent doctor Constantin Levaditi represents one of the most important researchers in the field of medicine in the 20th century. Although he was engaged in many areas of the rapidly growing field of immunology, his name is associated mainly with research in poliomyelitis. His laboratory research contributed decisively to the clarification of the epidemiology of this dreadful disease that claimed thousands of victims. Moreover, his experimental work constituted the basis for the development of the vaccine against poliomyelitis, initially in 1955 by Jonas Salk (1914-95) using inactivated virus, and then in 1960 by Albert Sabin (1906-93) who used live attenuated virus.