Rosalyn Sussman Yalow (July 19, 1921 – May 30, 2011) was an American medical physicist, and a co-winner of the 1977 Nobel Prize in Physiology or Medicine (together with Roger Guillemin and Andrew Schally) for development of the radioimmunoassay technique.

Yalow knew how to type, and was able to get a part-time position as a secretary to Dr. Rudolf Schoenheimer, a leading biochemist at Columbia University's College of Physicians and Surgeons.

She did not believe that any respectable graduate school would admit and financially support a woman, so she took another job as a secretary to Dr. Michael Heidelberger, another biochemist at Columbia, who hired her on the condition that she studied stenography.

Yalow saw the feminist movement as a challenge to her traditional beliefs and thought that it encouraged women not to fulfill their duties to become mothers and wives.

[5]: 109 The month after graduating from Hunter College in January 1941, Rosalyn Sussman Yalow was offered a position as a teaching assistant in the physics department of the University of Illinois at Urbana-Champaign.

Gaining acceptance to the physics graduate program in the college of engineering at the University of Illinois was one of the many hurdles she had to overcome as a woman in her field.

Powerful male figures controlled opportunities for training, recognition, promotion, and many aspects of development in the field of science, and especially physics.

[7] Yalow credited her position at the prestigious graduate school to the shortage of male candidates during World War II.

[5] During her time at the University of Illinois, she took extra undergraduate courses to increase her knowledge because she wanted to do original experimental research in addition to her regular teaching duties.

[5]: 76 [9] Yalow's first job after teaching and taking classes at the University of Illinois at Champaign-Urbana graduate school was as an assistant electrical engineer at Federal Telecommunications Laboratory.

[7] By 1950, Yalow had equipped a radioisotope laboratory at the Bronx VA Hospital and decided to leave teaching to finally devote her attention to full-time research.

There she collaborated with Solomon Berson to develop radioimmunoassay,[5] a radioisotope tracing technique that allows the measurement of tiny quantities of various biological substances in human blood as well as a multitude of other aqueous fluids.

Originally used to study insulin levels in diabetes mellitus, the technique has since been applied to hundreds of other substances – including hormones, vitamins and enzymes – all which had been present in quantities or concentrations that were previously too small to detect.

[7] Without the contributions of Yalow to the work of accurate hormone measurement, it was impossible to diagnose various hormone-related conditions and endocrine diseases like type 1 diabetes.

[14] Another mentee, Dr. Narayana Panicker Kochupillai, went on to become a leading endocrinology researcher in India, studying thyroid hormones and iodine deficiency.

"[13] Yalow was awarded a Fulbright fellowship to Portugal, which is an American scholarship program of competitive, merit-based grants that sponsor participants for exchanges in all areas of endeavor, including the sciences, business, academe, public service, government, and the arts.

Established by Albert and Mary Lasker in 1945, the award is intended to celebrate scientists who have made fundamental biological discoveries and clinical advances that improve human health.