Willem Johan "Pim" Kolff (February 14, 1911 – February 11, 2009) was a pioneer of hemodialysis, artificial heart, as well as in the entire field of artificial organs. Willem was a member of the Kolff family, an old Dutch patrician family. He made his major discoveries in the field of dialysis for kidney failure during the Second World War. He emigrated in 1950 to the United States, where he obtained US citizenship in 1955, and received a number of awards and widespread recognition for his work. Netherlands Born in Leiden, Netherlands, Kolff was the eldest of a family of 5 boys. Kolff studied medicine in his hometown at Leiden University, and continued as a resident in internal medicine at Groningen University. One of his first patients was a 22-year-old man who was slowly dying of chronic kidney failure. This prompted Kolff to perform research on artificial renal function replacement. Also during his residency, Kolff organized the first blood bank in Europe (in 1940). Kolff's first prototype dialyzer was developed in 1943, built from orange juice cans, used auto parts, and sausage casings. Over a two-year span, Kolff had attempted to treat 15 people with his machine, but all had died. In 1945, Kolff successfully treated his first patient, a 67-year-old woman, from kidney failure using his hemodialysis machine. During World War II, he was in Kampen, where he was active in the resistance against the German occupation. Simultaneously, Kolff developed the first functioning artificial kidney. He treated his first patient in 1943, and in 1945 he was able to save a patient's life with hemodialysis treatment. In 1946 he obtained a PhD degree summa cum laude at University of Groningen on the subject. It marks the start of a treatment that has saved the lives of millions of acute kidney injury or chronic kidney failure patients ever since. United States When the war ended, Kolff donated his artificial kidneys to other hospitals to spread familiarity with the technology. In Europe, Kolff sent machines to London, Amsterdam, and Poland. Another machine sent to Dr. Isidore Snapper at Mount Sinai Hospital in New York City was used to perform the first human dialysis in the United States on January 26, 1948 under the supervision of Drs. Alfred P. Fishman and Irving Kroop. In 1950, Kolff left the Netherlands to seek opportunities in the US. At the Cleveland Clinic, he was involved in