Rosalyn Yalow was awarded the Nobel Prize for
Physiology or Medicine in 1977, for the development of
radioimmunoassay of peptide hormones. This Foreword
was written for the second edition in 1999.
While some of my girlfriends aspired to be movie stars,
my great inspiration was Marie Curie. She set a wonderful
example to all women scientists. Throughout my life
I have been passionate about science and felt the need for
women to be treated equally to men, in science and in soci-
ety as a whole. I still believe in the value of science as a
powerful and positive inﬂuence for society. But over the
years I have realized that great science is rare. Where it
occurs, it should be cherished and nurtured.
Some readers may have assumed that I was a biologist or
medical researcher but I was neither. I graduated in Phys-
ics in the College of Engineering in New York, not far
from my home in the North Bronx, where I was raised as a
child and still live. I was the ﬁrst woman to take this course
since World War I. There was a shortage of male students
when I joined in September 1941; otherwise I doubt
I would have been accepted as a mere woman! I received
my Ph.D. at the University of Illinois, Champaign-Urbana,
and returned to work at the Veterans Administration Hos-
pital near my home in 1947. More than 50 years later,
I still work there for a few hours every day.
My collaborator, the late Solomon Berson, was a resident
at the hospital in July 1950. He was a brilliant registrar. He
was very good at mathematics and loved mathematical
puzzles. The discovery of immunoassay was part mathe-
matics, part physics, and part biology. I learned about biol-
ogy from Sol, and he learned about physics from me.
I believe that most scientiﬁc breakthroughs come out of
painstaking research and experimentation; these are neces-
sary precursors of those rare ﬂashes of inspiration. But
then, the most exciting new ideas can take a scientist into
unexpected new territory. We were working on a medical
problem involving diabetes, not trying to discover a new
assay technique, but after we did, it became a tool that was
used to investigate medical problems in a range of differ-
ent ﬁelds much wider than we could ever have imagined.
Sol and I were investigating the suggestion of Dr I.
Arthur Mirsky that maturity-onset diabetes might be due
to excessive enzymic degradation of insulin, rather than an
absolute deﬁciency of insulin secretion, which was the pre-
vailing theory at the time. We administered 131I-insulin to
diabetic and nondiabetic subjects and observed a slower
rate of disappearance of the labeled insulin from patients
who had been treated with insulin, whether or not they
were diabetic. We wondered whether antibodies had
developed to the animal-derived insulin, changing the rate
of disappearance. We used separation methods to prove
that the protein that bound insulin in the treated patients
was an antibody. This was something that immunologists
could not accept at the time and our paper was rejected by
Science and initially by the Journal of Clinical Investigation.
The aim of science is to make new discoveries, so it is
ironic that data that only conﬁrm what is already thought
is more likely to be published and that new discoveries are
often unwelcome to the scientiﬁc community. At my age
I can say what I think and not worry about the conse-
quences. Come to think of it, that’s how I have always been
and it is a necessary personality trait for a good scientist!
It is amazing that insulin had been given to patients
since 1920, yet no one had realized that there was an
immune reaction to it before. At the time, that was the
discovery we thought was the most signiﬁcant because of
its medical application, and immunoassay was very much a
We devised the principle of radioimmunoassay in 1956,
but it took a couple of years to get it to work. We published
our ﬁrst paper describing the immunoassay technique in
1959, but research papers that we published in the preced-
ing 2 years hint of our development work. The idea did not
come in a ﬂash of inspiration, but was the result of pains-
taking scientiﬁc method. We called the technique immuno-
assay, then radioimmunoassay, which is logical enough, but
I have to admit it has given people problems over the years
as it is rather a tongue twister. It quickly became RIA.
I should have learned from Marie Curie that a simple name
like x-ray would be easier to say and remember!
I am sometimes asked if I regret that we did not patent
the principle of immunoassay. Not only do I not regret it,
but I felt very strongly that we, as scientists, should not
seek to exploit our scientiﬁc discoveries for our own ﬁnan-
cial gain. We realized that our new technique could have
widespread applications, so we organized classes every year
and invited scientists from all over the world to come and
learn about our discovery, and how to develop their own
assays. This may help to explain why the technique quickly
spread to different analytes and many countries and why so
many companies eventually manufactured immunoassays.
I feel the same way about commercial links with manu-
facturers. I have declined lucrative offers to act as a paid
consultant for immunoassay companies. How could I have
retained my scientiﬁc integrity otherwise?
I had a wonderful time as a scientist. We had just a small
laboratory, and nobody bothered us. I had to build upon
my academic education, learning about medicine, so that
I could make a useful contribution to scientiﬁc knowledge,
then later on we had to set up educational courses to pass
on what we had learned. This is how good science should
be carried out and communicated. I believe that we were
successful because we always worked at the laboratory
bench and were only interested in discovering the truth.
I did not stop working at the bench until 1970, and I still
carry out scientiﬁc research from my desk for a few hours
every day. Over the years I carried out research into
glycoprotein heterogeneity and developed one of the ﬁrst
assays for Hepatitis B. Recently I have been studying the
effects of radioactivity on the environment.
Of 10 women Nobel Prize winners in Science at the
time of writing, I was the only one from an uneducated
family. By coincidence one of the others, Gertrude Elian,
also graduated from Hunter College in Manhattan.
I am immensely proud of my work with Sol. I hope that
does not sound arrogant. But I was lucky enough to see our
hard work amply rewarded by tangible results. I like to
think that Marie Curie would have been proud of me had
she known of my work. Perhaps she and Sol are having
heated debates about a controversial new theory as I write
this now. If so, there is indeed a heaven.