Rita was born into an intellectual family in Turin in 1909. She entered the University of Turin to study medicine, despite her father's belief that women should not pursue careers. She graduated summa cum laude in 1936, and then completed a degree for specialization in neurology and psychiatry.
The passage of the racial laws by the Fascist regime that barred Jews from Italian universities and other public institutions forced her to postpone the launch of her promising career. In spring 1940, she fled to Florence and lived underground with her parents and sisters until the end of World War II. Rita did not give up her research activities even in these troubled times. She set up a small laboratory in her bedroom, where she conducted experiments on the growth of nerve cells in chicken embryos.
In 1947, Rita accepted an invitation to Washington University in St. Louis. Although the initial invitation was for one semester, she stayed for thirty years, and in 1958 she was named a full professor.
With her collaborators, in 1948 Rita discovered that a certain type of mouse tumour had the capacity to greatly stimulate the proliferation of nerve fibres in host embryos.
They eventually attributed this effect to the protein they called the nerve growth factor (NGF). Levi-Montalcini proved that tumour was able to cause similarly excessive and precocious production and abnormal distribution of nerve fibres in vitro culture units as well. It was biochemist Stanley Cohen who isolated NFG from the tumour. This was the first of the numerous cell-growth factors found in animals.
In 1986, shared with Stanley Cohen, Rita was a Nobel Prize laureate in Medicine for the discoveries of growth factors. Today (2010) she is the oldest living Nobel Prize winner.