Luis Federico Leloir was born on September 6, 1906, in Paris, France. Leloir's parents, Federico and Hortensia Aguirre Leloir, were in France only for a visit when Leloir was born, and returned to their home in Buenos Aires, Argentina, when he was two years old. Leloir grew up in a house filled with books on a variety of topics. He enrolled at the University of Buenos Aires to study medicine, and graduated with a medical degree in 1932.

Leloir found medicine somewhat limited in terms of the treatment options available at the time, and had no confidence in his own ability to diagnose and treat his patients. Therefore, he decided to try a position in research at the Institute of Physiology at the University of Buenos Aires to help develop new options in treatment for physicians and to work on a Ph.D. degree. He worked under Bernardo Houssay, a Nobel...