The women's 100 metre butterfly event at the 2003 World Aquatics Championships took place between 20 July – 21 July. Both the heats and semifinals were held on 20 July with the heats being held in the morning session and the semifinals being held in the evening session. The final was held on 21 July.

Records

Prior to the competition, the existing world and championship records were as follows.

	Name	Nationality	Time	Location	Date
World record	Inge de Bruijn Inge de Bruijn Inge de Bruijn is a Dutch former swimmer. She was a four-time Olympic champion and a former world record holder.-Biography:De Bruijn was born in Barendrecht, South Holland, and tried several sports before settling with swimming....	Netherlands Netherlands The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...	56.61	Sydney Sydney Sydney is the most populous city in Australia and the state capital of New South Wales. Sydney is located on Australia's south-east coast of the Tasman Sea. As of June 2010, the greater metropolitan area had an approximate population of 4.6 million people...	17 September 2000
Championship record	Petria Thomas Petria Thomas Petria Ann Thomas OAM is an Australian swimmer and Olympic gold medallist and a winner of 15 national titles. She was born in Lismore, New South Wales and grew up in the nearby town of Mullumbimby....	Australia Australia Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...	58.27	Fukuoka Fukuoka Fukuoka most often refers to the capital city of Fukuoka Prefecture.It can also refer to:-Locations:* Fukuoka, Gifu, a town in Gifu Prefecture, Japan* Fukuoka, Toyama, a town in Toyama Prefecture, Japan...	28 July 2001

The following records were established during the competition:

Date	Round	Name	Nationality	Time	WR	CR
July 20	Heats	Jenny Thompson Jenny Thompson Jennifer Beth Thompson is an American former competitive swimmer, and one of the most decorated Olympians in history, winning twelve medals, including eight gold medals , in the 1992, 1996, 2000, and 2004 Summer Olympics.Thompson, a Massachusetts native who calls Dover, New Hampshire her...	United States United States The United States of America is a federal constitutional republic comprising fifty states and a federal district...	58.14		CR
July 20	Semifinals	Jenny Thompson Jenny Thompson Jennifer Beth Thompson is an American former competitive swimmer, and one of the most decorated Olympians in history, winning twelve medals, including eight gold medals , in the 1992, 1996, 2000, and 2004 Summer Olympics.Thompson, a Massachusetts native who calls Dover, New Hampshire her...	United States United States The United States of America is a federal constitutional republic comprising fifty states and a federal district...	57.99		CR
July 21	Final	Jenny Thompson Jenny Thompson Jennifer Beth Thompson is an American former competitive swimmer, and one of the most decorated Olympians in history, winning twelve medals, including eight gold medals , in the 1992, 1996, 2000, and 2004 Summer Olympics.Thompson, a Massachusetts native who calls Dover, New Hampshire her...	United States United States The United States of America is a federal constitutional republic comprising fifty states and a federal district...	57.96		CR

Final

Rank	Name	Nationality	Time	Notes
	Jenny Thompson Jenny Thompson Jennifer Beth Thompson is an American former competitive swimmer, and one of the most decorated Olympians in history, winning twelve medals, including eight gold medals , in the 1992, 1996, 2000, and 2004 Summer Olympics.Thompson, a Massachusetts native who calls Dover, New Hampshire her...		57.96	CR
	Otylia Jędrzejczak Otylia Jedrzejczak Otylia Jędrzejczak is a Polish swimmer. She is the Olympic champion from Athens 2004 in the 200 metre butterfly. She finished 4th in this event in the 2008 Summer Olympics in Beijing. She also swam in a third Olympiad, at the 2000 Summer Olympics in Sydney. In Athens 2004 she also silvered in...		58.22
	Martina Moravcová Martina Moravcová Martina Moravcová is a medley, butterfly and freestyle swimmer from Slovakia. She made her international swimming debut in 1991 for Czechoslovakia, and has gone on to compete in five consecutive Summer Olympics...		58.24
4	Alena Popchanka Alena Popchanka Alena Popchanka is a 4-time Olympic freestyle and butterfly swimmer originally from Belarus. She swam for Belarus at the 1996, 2000 and 2004 Olympics...		58.90
5	Yafei Zhou		59.08
6	Anna-Karin Kammerling Anna-Karin Kammerling Anna-Karin Kammerling is a world-record breaking Swedish swimmer, who was born in Malmö, Sweden. Currently she resides in Sundsvall and trains with the Sundsvalls Swim Club under coach Hans Bergquist....		59.14
7	Yuko Nakanishi Yuko Nakanishi is a Japanese butterfly swimmer.- Major achievements :2000 Sydney Olympics*200m butterfly 7th 2004 Athens Olympics*100m butterfly 14th...		59.32
8	Natalie Coughlin Natalie Coughlin Natalie Anne Coughlin is an American swimmer and eleven-time Olympic medallist.At the 2008 Summer Olympics, Coughlin became the first American female athlete in modern Olympic history to win six medals in one Olympics and the first woman ever to win a 100 m backstroke gold in two consecutive...		59.63

Key: CR = Championship record