In 1960, Varsavsky returned to Argentina, where he joined the newly created group of Astrophysics at the University of Buenos Aires and worked as senior lecturer in physics until 1966. He was the founder and first director of the Argentine Institute of Radio Astronomy, founded in 1964, and president of the Association of Physics in Argentina. Furthermore, he participated in the construction of the largest radio telescope in the Southern Hemisphere, which is located in Villa Elisa, Buenos Aires.