Jarmila Kratochvílová (Czech pronunciation: [ˈjarmɪla ˈkratoxviːlovaː]; born 26 January 1951, in Golčův Jeníkov) is a Czech former track and field athlete. She won the 400 metres and 800 metres at the 1983 World Championships, setting a world record in the 400 m. In 1983, she also set the world record for the 800 metres, which still stands and which is currently the longest-standing individual world record in athletics. Only one athlete, Pamela Jelimo of Kenya, in 2008, has come within a second of Kratochvílová's mark since it was set.
In 1983, Kratochvílová broke the 800 m world record with a time of 1:53.28. At the World Championships shortly afterwards, she won the 800 m and set a world record of 47.99 seconds to win the 400 m.
Kratochvílová's 1983 400-metre world record of 47.99 seconds stood for only two years until it was broken by her great rival Marita Koch in 1985. Koch's 400-metre world record of 47.60 seconds still stands as of 2016. Koch and Kratochvílová are the only women who have broken the 48 second barrier in a 400-metre laned race. Her 800-metre world record is the longest standing track record in men or women's athletics, and was described by 1996 Olympic champion Svetlana Masterkova as ".. very fast. It's impossible for women to run so fast. It will last for 100 years."
Kratochvílová was a late developer, not breaking 53 seconds for the 400 metres until she was 27, and she was 32 when she set her world records. Her remarkably fast times, and her atypical muscular physique spawned rumors of illegal drug use. Kratochvílová has maintained her innocence, and although in 2006 the Prague newspaper Mladá fronta DNES claimed to have uncovered a doping program run by Czechoslovakia's Communist government, there was no link to Kratochvílová despite her being her country's highest profile athlete.
Since her retirement Kratochvílová has worked as an athletics coach and with the Czech national team.