| 2009 FINA World Championships | ||
|---|---|---|
| Diving | ||
| Individual | ||
| 1 m | men | women |
| 3 m | men | women |
| 10 m | men | women |
| Synchronised | ||
| 3 m | men | women |
| 10 m | men | women |
| Open water swimming | ||
| 5 km | men | women |
| 10 km | men | women |
| 25 km | men | women |
| Swimming | ||
| Freestyle | ||
| 50 m | men | women |
| 100 m | men | women |
| 200 m | men | women |
| 400 m | men | women |
| 800 m | men | women |
| 1500 m | men | women |
| Backstroke | ||
| 50 m | men | women |
| 100 m | men | women |
| 200 m | men | women |
| Breaststroke | ||
| 50 m | men | women |
| 100 m | men | women |
| 200 m | men | women |
| Butterfly | ||
| 50 m | men | women |
| 100 m | men | women |
| 200 m | men | women |
| Individual medley | ||
| 200 m | men | women |
| 400 m | men | women |
| Freestyle relay | ||
| 4 × 100 m | men | women |
| 4 × 200 m | men | women |
| Medley relay | ||
| 4 × 100 m | men | women |
| Synchronised swimming | ||
| Solo | ||
| Technical | women | |
| Free | women | |
| Duet | ||
| Technical | women | |
| Free | women | |
| Team | ||
| Technical | women | |
| Free | women | |
| Combination | women | |
| Water polo | ||
| Tournament | men | women |
The heats for the women's 50 m butterfly race at the 2009 World Championships took place in the morning and evening of 31 July, with the final in the evening session of 1 August at the Foro Italico in Rome, Italy.
Prior to this competition, the existing world and competition records were as follows:
| World record | 25.33 | Amsterdam, Netherlands | 19 April 2009 | |
| Championship record | 25.82 | Melbourne, Australia | 30 March 2007 |
The following records were established during the competition:
| Date | Round | Name | Nationality | Time | Record |
|---|---|---|---|---|---|
| 31 July | Heat 10 | Sarah Sjöström | | 25.74 | CR |
| 31 July | Heat 13 | Therese Alshammar | | 25.44 | CR |
| 31 July | Semifinal 1 | Marleen Veldhuis | | 25.28 | WR |
| 31 July | Semifinal 2 | Therese Alshammar | | 25.07 | WR |
| Rank | Name | Nationality | Time | Heat | Lane | Notes |
|---|---|---|---|---|---|---|
| 1 | Therese Alshammar | 25.07 | 2 | 4 | WR | |
| 2 | Marleen Veldhuis | 25.28 | 1 | 4 | NR | |
| 3 | Ingvild Snildal | 25.53 | 2 | 5 | NR | |
| 4 | Marieke Guehrer | 25.58 | 2 | 3 | OC | |
| 5 | Yafei Zhou | 25.59 | 1 | 6 | AS | |
| 6 | Sarah Sjöström | 25.76 | 1 | 5 | ||
| 7 | Daynara de Paula | 25.85 | 2 | 7 | SA | |
| 8 | Diane Bui Duyet | 25.87 | 2 | 8 | NR | |
| 9 | Jeanette Ottesen | 25.90 | 2 | 6 | ||
| 10 | Hinkelien Schreuder | 25.94 | 1 | 7 | ||
| 11 | Silvia di Pietro | 26.00 | 1 | 3 | ||
| 12 | Sviatlana Khakhlova | 26.00 | 2 | 1 | ||
| 13 | Gabriella Silva | 26.02 | 1 | 2 | ||
| 14 | Triin Aljand | 26.16 | 1 | 1 | ||
| 15 | Christine Magnuson | 26.21 | 2 | 2 | ||
| 16 | Daniela Samulski | 26.33 | 1 | 8 | NR |
| Rank | Name | Nationality | Time | Lane | Notes |
|---|---|---|---|---|---|
| Marieke Guehrer | 25.48 | 6 | OC | ||
| Yafei Zhou | 25.57 | 2 | AS | ||
| Ingvild Snildal | 25.58 | 3 | |||
| 4 | Therese Alshammar | 25.59 | 4 | ||
| 5 | Marleen Veldhuis | 25.63 | 5 | ||
| 6 | Sarah Sjöström | 25.66 | 7 | ||
| 7 | Diane Bui Duyet | 25.92 | 8 | ||
| 8 | Daynara de Paula | 26.12 | 1 |