International Physicians for the Prevention of Nuclear War (IPPNW) is a worldwide grouping of 62 national medical organizations. IPPNW uses research, education and advocacy to help prevent nuclear war and encourage the abolition of all nuclear weapons. By the mid-1980s IPPNW had around 145,000 members and by the early 1990s around 200,000 members from over sixty countries. The group headquarters is in Union Square of Somerville, Massachusetts.
The IPPNW was founded in December 1980 by the cardiologists Dr. Bernard Lown of the Harvard School of Public Health and Dr. Evgueni Chazov of the USSR Cardiological Institute. Based on research they produced a "medical warning to humanity" of the medical and environmental dangers of nuclear war. The group's campaign produced books and also articles for professional journals and more popular media. IPPNW was awarded the UNESCO Peace Education Prize in 1984 and the Nobel Peace Prize in 1985.
IPPNW has extended its original four point mandate to include the prevention of all wars, and advancing understanding of the causes of armed conflict from a public health perspective.
In April 2006 it published a report criticizing the September 2005 United Nations report on the 1986 Chernobyl disaster, which claimed that only 47 direct deaths could be attributed to the disaster. On 31 April 2007, it launched the International Campaign to Abolish Nuclear Weapons in Vienna, Austria, at the first session for the 2010 review conference for the parties to the Treaty on the Non-Proliferation of Nuclear Weapons.