[2] Rao's research started in the field of toxicology, studying proteolytic enzymes in the venom from various snake species.
[2] Her field in later life was reproductive immunology; she studied human chorionic gonadotropin,[4] and the presence of antigens in sperm as a cause for infertility.
[2] She worked with the United Nations Economic and Social Commission for Asia and the Pacific (ESCAP), and with the World Health Organization, serving on WHO's Committee on Immunological Aspects of Reproduction.
[1] In 1963, she was one of the four Indian scientists to win the G. J. Watumull Memorial Prize, for her work in family planning.
[15][16] In 1965, she won a grant from the Rockefeller Foundation to visit reproductive physiology laboratories in Europe and Israel.