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Portrait of Karl Landsteiner
Photo: Bachrach Studios, [2] · Public domain via Wikimedia Commons

Nobel Prize in Physiology or Medicine · 1930

Karl Landsteiner

He discovered the human blood groups, the key to turning blood transfusion from a deadly gamble into routine, life-saving medicine.

The Nobel citation: “for his discovery of human blood groups”
Born
June 14, 1868, Vienna, Austrian Empire (now Austria)
Died
June 26, 1943, New York, NY, USA
Affiliation at the time
Rockefeller Institute for Medical Research, USA

Medicine prize

1930

Awarded alone.

Age that year

62years

Born in 1868.

Headline credited impact

18–60million lives saved

Lives saved worldwide by blood-group-matched transfusion. How it was built

Sources cited

24

Fact-checked September 24, 2026.

  • He found the blood groups in 1901 by mixing his own blood with blood from colleagues in his Vienna lab.
  • World Blood Donor Day is held every 14 June because that is Landsteiner's birthday.
  • He also co-discovered the Rh factor and, with Erwin Popper, showed that polio is caused by a virus.
  • In 1911 the University of Vienna made him a professor, but without a salary.
  • He was still doing experiments at 75 when he suffered a fatal heart attack in his laboratory in 1943.

The breakthrough

Discovering the human blood groups (1901)

Around 1900, doctors knew that giving a patient another person's blood sometimes saved a life and sometimes killed. Nobody knew why, so transfusion had been almost abandoned. Landsteiner, a young pathologist in Vienna, tried a simple experiment. He drew blood from himself and his colleagues, split each sample into red cells and serum (the clear liquid part), and mixed each person's serum with everyone else's cells. Often nothing happened. But some pairs made the red cells clump together, a reaction called agglutination. The pattern was regular, and in 1901 he showed that people fall into distinct groups, which he called A, B and C (now called O). Two colleagues found a fourth group, AB, the next year. The reason is that red cells carry markers on their surface, and each person's serum naturally holds antibodies against the markers their own cells lack. It works like a security system: the guards in your blood grab any badge your own cells do not wear. If a patient gets cells with the wrong badges, the clumped cells can block vessels and burst, causing shock, jaundice and even death. Matching donor and patient by group prevents this. Landsteiner also pointed out that grouping could help trace the source of a bloodstain, and suggested that because blood groups are inherited, they could help settle disputed paternity. Later, in New York, he and his colleagues found more blood groups, including M, N and the Rh factor.[2],[3],[4],[5],[6],[10],[11],[12]

“The simple solution to the problem was provided by the discovery of individual differences in blood, and of the blood groups.”
Karl Landsteiner, Nobel Lecture, 11 December 1930, explaining why transfusions between people had so often been dangerous (English translation published by the Nobel Foundation).[3]

What it meant for humanity

Before 1901, transfusion was a last resort that often killed, and doctors had largely given it up. Landsteiner's discovery explained those deaths and showed how to avoid them: test the blood groups and match donor to patient. Practice caught up slowly. In 1907 the New York doctor Reuben Ottenberg first matched blood before a transfusion, and in 1915 the anticoagulant sodium citrate made it possible to store blood. During World War I, transfusion was used on a large scale for the first time, and it has been standard ever since. Operations once ruled out by blood loss became survivable. Today about 120 million blood donations are collected worldwide each year. In poorer countries it is used most often for complications of pregnancy and for children with severe anemia; in richer ones, for heart surgery, transplants, major trauma and cancer care. In its 1998-1999 global survey, the World Health Organization said transfusions save millions of lives every year, while warning that up to 150,000 pregnancy-related deaths a year could still be prevented with adequate transfusion. His later discovery of the Rh factor with Alexander Wiener helped explain a disease in which a mother's antibodies attack her baby's blood, and led to a preventive treatment in the 1960s. Blood typing also helps match organ transplants and identify bloodstains in criminal cases. With Erwin Popper he found in 1908 that polio is caused by an infectious agent, apparently a virus, a first step toward the vaccines that came decades later. His studies of haptens, small molecules that trigger antibodies only when attached to a protein, showed how the immune system recognizes chemical shapes.

  • About 120 million blood donations are collected worldwide each year, and matching the ABO and Rh groups he helped discover is the key to giving that blood safely.[5],[13]
  • The World Health Organization reported in its 1998-1999 global survey that blood transfusions save millions of lives every year.[14]
  • With Alexander Wiener he reported the Rh factor in 1940. It was soon shown to cause a deadly blood disease of newborns, and a preventive treatment developed in the 1960s sharply reduced it.[6],[10],[11]
  • In 1908 he and Erwin Popper transmitted polio to monkeys and concluded that a virus caused it, groundwork for the vaccines that have spared an estimated 20 million people from paralysis since 1988.[6],[11],[20]
  • His work on haptens laid the chemical basis of how antibodies recognize their targets, and showed how simple chemicals can cause skin allergies.[6]
  • World Blood Donor Day, first held in 2004 and made an annual global event by WHO member states in 2005, falls on 14 June, his birthday.[5],[21]

Impact in numbers

Landsteiner's blood groups are the reason transfusion went from a gamble to a routine treatment, supplied today by about 120 million blood donations a year. We model the lives saved by matched transfusion since 1915 at roughly 60 to 200 million and credit him 30%, because matching was useless until others learned to store blood, cross-match it, bank it and screen it for infection. Popular claims that his work saved a billion lives are unsourced, so we stay well below them. We also credit him a small share of the polio paralysis prevented by vaccines, since his 1908 work with Erwin Popper first pointed to a virus as the cause. Much of his impact resists numbers: blood typing in forensic science and paternity cases, matching for organ transplants, the Rh discovery behind the prevention of a deadly disease of newborns, and his chemical explanation of how antibodies recognize their targets, which shaped immunology and allergy research.

HealthFundamental science

Each number is the laureate’s credited share of a real-world outcome, cumulative to 2025. The whole outcome, the share of credit, and the reasoning are shown so you can check the arithmetic. Outcomes shared with other laureates are counted once on the impact page.

  • Low confidenceDirectModeledHealth

    Lives saved worldwide by blood-group-matched transfusion

    18–60

    million lives saved, credited share

    That is 30% of 60–200 million lives saved since 1915.

    How this number was built

    Units: WHO counted over 75M donations a year in 1998-99 and 120.4M in 2023; a straight line from 1998 through 2025 gives about 2.8B units. For 1915-1997 we assume 1.0B (low) to 2.2B (high, a steady rise from near zero in 1940 to 75M in 1998). Total 3.8B-5.0B units. The Red Cross says the average red-cell transfusion is about 3 units, so 1.27B-1.67B transfusions. We assume 5% (low) to 12% (high) of them averted a death (an unsourced judgment, hence low confidence): 63M-200M, rounded to 60M-200M. At 1998 volumes that is 1.25M-3M lives a year, consistent with WHO's statement that transfusion saves millions of lives yearly. Popular claims of 1 billion lives are unsourced; we stay far below. Share 0.3: his ABO and Rh discoveries were the precondition, but cross-matching, citrate storage, blood banking and infection screening by others were also essential.[6],[13],[14],[15],[16]

    Sources: World Health Organization; World Health Organization; American Red Cross; HumanProgress.org (Cato Institute); National Academy of Sciences, Biographical Memoirs vol. 40

  • Low confidenceRippleSourced totalHealth

    People spared polio paralysis by vaccination since 1988

    360,000–440,000

    people benefited, credited share

    That is 2% of 18–22 million people benefited since 1988.

    How this number was built

    The Global Polio Eradication Initiative states that since 1988, 20 million people are walking who would otherwise have been paralyzed by polio. We use 18M-22M to reflect uncertainty in that modeled figure, and we leave out gains before 1988, so the total is conservative. Share 0.02: Landsteiner and Popper's 1908 finding that polio is caused by a transmissible agent, apparently a virus (Flexner and Lewis reached it independently in 1909), was an essential first step, but the vaccines required decades of later work, including Jonas Salk's and Albert Sabin's vaccines, plus mass immunization campaigns reaching billions of children.[2],[6],[11],[20]

    Sources: Global Polio Eradication Initiative; National Academy of Sciences, Biographical Memoirs vol. 40; NobelPrize.org (from Nobel Lectures, Physiology or Medicine 1922-1941, Elsevier, 1965); Cureus, via PubMed Central

  • Low confidenceRippleModeledHealth

    Fetal and newborn deaths from Rh disease prevented by anti-D immunoglobulin, 1968-2025

    45,000–70,000

    lives saved, credited share

    That is 1% of 4.5–7 million lives saved since 1968.

    How this number was built

    Landsteiner and Wiener found the Rh antigen in 1940, the cause of hemolytic disease of the newborn (s10, s6). Anti-D immunoglobulin (licensed 1968) stops Rh-negative mothers forming antibodies. FIGO/ICM (s22): Rh disease still causes >160,000 perinatal deaths a year, only 50% below the pre-anti-D era, as about half of eligible women go without it (s23). So about 160,000 are averted a year now. Low: linear rise from 0 in 1968 to 160,000 in 2025: 58 x 80,000 = 4.6M (4.5M). High: rise complete by 1995 (rich countries adopted within a year, s24), then flat: 28 x 80,000 + 30 x 160,000 = 7.0M. Check: about 10,000 US newborn deaths a year before 1968 (s24). Prevented cases never needed transfusion: no overlap with that claim. Share 0.01: Wiener co-discovered Rh; Levine and Stetson found the antibody (1939) and tied it to the disease; Freda, Gorman, Pollack, Finn, Clarke made the prophylaxis.[6],[10],[22],[23],[24]

    Sources: Rockefeller University Hospital Centennial; National Academy of Sciences, Biographical Memoirs vol. 40; International Journal of Gynecology & Obstetrics (via PubMed Central); PLOS One; Columbia University Irving Medical Center

The double edge

Landsteiner's discovery was not itself used to hurt people, but blood-group science was bent toward racism. In the decades after his discovery, and years before the Nazis took power, some scientists used the uneven spread of blood groups across populations to build theories of blood purity and racial superiority. Even the 1930 Nobel presentation speech presented blood groups as a new tool for studying the racial purity of a people. Transfusion also carries real risks when safety systems fail. Mismatched or unnecessary transfusions can cause serious reactions, and unscreened blood can spread infections: in the United Kingdom, an official inquiry estimated that more than 3,000 deaths were attributable to infected blood and blood products. These harms came from misuse and from failures of screening and regulation, not from the discovery of blood groups.

  • Moderate

    Blood groups misused in race theories

    In the years after World War I, well before the Nazis took power, some scientists used the uneven spread of blood groups across populations to rank peoples and promote ideas of blood purity. The 1930 Nobel presentation speech itself described blood groups as opening research into the racial purity of a people.[4],[18]

  • Moderate

    Infections spread through contaminated blood

    Blood that is not properly screened can transmit HIV, hepatitis and other infections. In the UK contaminated-blood scandal, the Infected Blood Inquiry's best estimate is that more than 3,000 deaths are attributable to infected blood, blood products and tissue. WHO still urges screening of all donated blood.[13],[19]

Against the odds

Landsteiner grew up in Vienna as antisemitism became a mass political force. In 1897 Karl Lueger became the city's mayor, and his Christian Social party used hostility toward Jews to rally voters. Landsteiner's father died when he was six, and his mother raised him alone. Around 1890, as a medical student, he and his mother converted to Catholicism; one medical history says the step was partly practical, because being Jewish could block a university career. Conversion did not bring quick success. Despite a string of major discoveries, he was made a professor only in 1911, a decade after his blood-group discovery, and even then without a salary. When he won the Nobel Prize, Austrian newspapers wrote that the University of Vienna had for years blocked his promotion because he was the son of a Jewish journalist. After World War I, Vienna was poor and unstable, research facilities were lacking, and Rockefeller University's history notes that antisemitism in postwar Austria made it hard for him to advance. He left in 1919 for a small hospital in The Hague and in 1923 moved to New York. He was not fleeing for his life, but hardship and prejudice pushed him out. Even in America he feared the label: in 1937 he sued to keep his name out of a directory of prominent American Jews, saying it would hurt him.

  • 1890

    Discrimination

    Around 1890, as Vienna's political antisemitism grew, Landsteiner and his widowed mother converted from Judaism to Catholicism. One medical history says the conversion was partly expedient, because being Jewish could close off a university career in Austria-Hungary.[6],[12],[17]

  • 1911

    Discrimination

    After more than a decade of major research, the University of Vienna appointed him an adjunct professor only in 1911, and without a salary. In 1930 Austrian newspapers said the university had long blocked his professorship because he was the son of a Jewish journalist.[2],[6],[8]

  • 1919

    Poverty

    After World War I, Vienna offered him little laboratory space, political unrest and constant money worries, so he took a post at a small Catholic hospital in The Hague. Rockefeller University's history adds that postwar antisemitism in Austria made it hard for him to advance.[6],[9]

  • 1937

    Other

    In 1937 he sought a court order to keep his biography out of Who's Who in American Jewry and asked for damages if it appeared, saying that publicly stressing his ancestors' religion would harm his private life and profession.[7]

Jewish background

Both parents JewishConverted to another faith

Landsteiner was born in Vienna to Jewish parents, the journalist and editor Leopold Landsteiner and Fanny Hess. His father died when he was six. Some years later, around 1890, he and his mother left Judaism and became Roman Catholics. He did not identify as Jewish as an adult. In 1937, living in New York, he went to court to keep his biography out of the book Who's Who in American Jewry, saying that publicly stressing the religion of his ancestors would harm his private life and career. He meets this site's standard through both parents.[2],[6],[7],[12]

Key dates

  1. June 14, 1868

    Born in Vienna to Jewish parents, the journalist Leopold Landsteiner and Fanny Hess.[1],[2],[6]

  2. 1890

    He and his widowed mother leave Judaism and become Roman Catholics.[6],[12]

  3. 1891

    Graduates in medicine from the University of Vienna, then spends several years studying chemistry with leading chemists in Germany and Switzerland.[2],[6]

  4. 1901

    Publishes his discovery that human blood falls into groups, which he calls A, B and C (now O).[4],[6]

  5. 1908

    Becomes chief of pathology at Vienna's Wilhelmina Hospital; with Erwin Popper, transmits polio to monkeys and concludes that a virus causes it.[6]

  6. 1911

    Appointed professor of pathological anatomy at the University of Vienna, but without a salary.[2],[6]

  7. 1916

    Marries Helene Wlasto; their only child, Ernst Karl, is born a year later.[2],[6]

  8. 1919

    Leaves impoverished postwar Vienna to work as a pathologist at a small Catholic hospital in The Hague.[2],[6],[9]

  9. 1923

    Moves with his family to New York to join the Rockefeller Institute for Medical Research as a full member.[6],[9]

  10. 1927

    With Philip Levine, discovers the M, N and P blood groups.[11]

  11. December 10, 1930

    Receives the Nobel Prize in Physiology or Medicine for his discovery of human blood groups.[1],[4]

  12. 1937

    Goes to court in New York to keep his biography out of Who's Who in American Jewry.[7]

  13. 1940

    With Alexander Wiener, reports the Rh factor, later shown to be behind a deadly blood disease in newborns.[6],[10]

  14. June 26, 1943

    Dies in New York, two days after a heart attack in his laboratory, still at work at 75.[1],[2]

Sources

  1. 1.Karl Landsteiner - Facts · NobelPrize.org (Nobel Prize Outreach)
  2. 2.Karl Landsteiner - Biographical · NobelPrize.org (from Nobel Lectures, Physiology or Medicine 1922-1941, Elsevier, 1965), 1965
  3. 3.On Individual Differences in Human Blood (Nobel Lecture, 11 December 1930) · NobelPrize.org, 1930
  4. 4.The Nobel Prize in Physiology or Medicine 1930 - Presentation Speech by G. Hedren · NobelPrize.org, 1930
  5. 5.Finding the key to safe blood transfusions · NobelPrize.org (Nobel Prize Outreach)
  6. 6.Karl Landsteiner 1868-1943: A Biographical Memoir (by Michael Heidelberger) · National Academy of Sciences, Biographical Memoirs vol. 40, 1969
  7. 7.Dr. Landsteiner Sues to Escape Being Labelled Jew · Jewish Telegraphic Agency, 1937
  8. 8.Landsteiner, Nobel Prize Winner, Left Vienna Because of Anti-semitism, Austrian Papers Say · Jewish Telegraphic Agency, 1930
  9. 9.Landsteiner, Karl (faculty member profile) · Rockefeller University, Digital Commons @ RU
  10. 10.The Rh Factor: Enhancing the Safety of Blood Transfusion and Setting the Stage for Preventing Hemolytic Disease of the Newborn · Rockefeller University Hospital Centennial
  11. 11.Karl Landsteiner (1868-1943): A Versatile Blood Scientist (Mohd Noor and Siti Asmaa, Cureus 16(9): e68903) · Cureus, via PubMed Central, 2024
  12. 12.Karl Landsteiner (1868-1943): Originator of ABO blood classification (Tan and Graham, Singapore Med J 54(5): 243-244) · Singapore Medical Journal, 2013
  13. 13.Blood safety and availability (fact sheet) · World Health Organization, 2025
  14. 14.Global Database on Blood Safety: Summary Report 1998-1999 · World Health Organization
  15. 15.Blood Needs and Blood Supply · American Red Cross
  16. 16.Heroes of Progress, Pt. 4: Landsteiner and Lewisohn · HumanProgress.org (Cato Institute)
  17. 17."I decide who is a Jew" (The First World War and the End of the Habsburg Monarchy) · Schloss Schoenbrunn Kultur- und Betriebsges.m.b.H., Vienna
  18. 18.Blood Purity: How a Bizarre Obsession Advanced Science · ABC News (from Der Spiegel), 2013
  19. 19.Infected Blood Inquiry Final Report, 20 May 2024 · Haemophilia Scotland, 2024
  20. 20.GPEI general fact sheet (September 2025) · Global Polio Eradication Initiative, 2025
  21. 21.World Blood Donor Day · World Health Organization, Western Pacific Region
  22. 22.FIGO/ICM guidelines for preventing Rhesus disease: A call to action (Visser GHA et al., Int J Gynaecol Obstet 152:144-147) · International Journal of Gynecology & Obstetrics (via PubMed Central), 2021
  23. 23.Hemolytic disease of the fetus and newborn due to Rh(D) incompatibility: A preventable disease that still produces significant morbidity and mortality in children (Pegoraro V et al., PLoS One 15:e0235807) · PLOS One, 2020
  24. 24.RhoGAM at 50: A Columbia Drug Still Saving Lives of Newborns · Columbia University Irving Medical Center, 2018

Fact-checked on September 24, 2026 by a separate AI fact-checking pass that re-opened the sources, with 12 corrections made. How we check

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