# Swimming at the 2003 World Aquatics Championships – Men's 100 metre breaststroke

The Men's 100 Breaststroke event at the 10th FINA World Aquatics Championships swam on 20–21 July 2003 in Barcelona, Spain. Preliminary and Semifinal heats swam on 20 July, with the Final on 21 July.
At the start of the event, the existing World (WR) and Championship (CR) records were both:

## Results
### Final

| Place | Swimmer | Nation | Time | Notes |
| 1 | Kosuke Kitajima | Japan | 59.78 | WR |
| 2 | Brendan Hansen | USA | 1:00.21 | |
| 3 | James Gibson | Great Britain | 1:00.37 | |
| 4 | Ed Moses | USA | 1:00.87 | |
| 5 | Morgan Knabe | Canada | 1:01.07 | |
| 6 | Domenico Fioravanti | Italy | 1:01.23 | |
| 7 | Darren Mew | Great Britain | 1:01.36 | |
| 8 | Hugues Duboscq | France | 1:01.48 | |

### Semifinals

| Rank | Heat + Lane | Swimmer | Nation | Time | Notes |
| 1 | S2 L4 | Kosuke Kitajima | Japan | 59.98 | q |
| 2 | S1 L4 | James Gibson | Great Britain | 1:00.47 | q |
| 3 | S1 L6 | Ed Moses | USA | 1:00.77 | q |
| 4 | S2 L6 | Brendan Hansen | USA | 1:00.83 | q |
| 5 | S1 L5 | Hugues Duboscq | France | 1:00.98 | q |
| 6 | S2 L5 | Morgan Knabe | Canada | 1:01.05 | q |
| 7 | S1 L8 | Domenico Fioravanti | Italy | 1:01.46 | q |
| 8 | S2 L1 | Darren Mew | Great Britain | 1:01.60 | q |
| 9 | S1 L3 | Oleg Lisogor | Ukraine | 1:01.65 | q |
| 10 | S2 L3 | Brenton Rickard | Australia | 1:01.77 | q |
| 11 | S2 L2 | Roman Ivanovski | Russia | 1:01.93 | q |
| 12 | S1 L7 | Martin Gustavsson | Sweden | 1:01.94 | q |
| 13 | S1 L1 | Mike Brown | Canada | 1:02.06 | q |
| 13 | S2 L8 | Emil Tahirovič | Slovenia | 1:02.06 | q |
| 15 | S1 L2 | Jarno Pihlava | Finland | 1:02.18 | q |
| 16 | S2 L7 | Mark Warnecke | Germany | 1:02.44 | q |

### Preliminaries

| Rank | Heat+Lane | Swimmer | Nation | Time | Notes |
| 1 | H13 L4 | Kosuke Kitajima | Japan | 1:00.20 | q |
| 2 | H13 L5 | James Gibson | Great Britain | 1:00.74 | q |
| 3 | H11 L5 | Morgan Knabe | Canada | 1:01.19 | q |
| 4 | H12 L3 | Hugues Duboscq | France | 1:01.35 | q |
| 5 | H11 L1 | Brenton Rickard | Australia | 1:01.37 | q |
| 6 | H11 L4 | Oleg Lisogor | Ukraine | 1:01.40 | q |
| 7 | H12 L5 | Brendan Hansen | United States | 1:01.47 | q |
| 8 | H12 L4 | Ed Moses | United States | 1:01.51 | q |
| 9 | H11 L2 | Roman Ivanovski | Russia | 1:01.78 | q |
| 10 | H11 L3 | Jarno Pihlava | Finland | 1:01.79 | q |
| 11 | H09 L1 | Mark Warnecke | Germany | 1:01.86 | q |
| 12 | H13 L7 | Martin Gustavsson | Sweden | 1:01.90 | q |
| 13 | H13 L3 | Darren Mew | Great Britain | 1:01.96 | q |
| 14 | H12 L1 | Mike Brown | Canada | 1:02.00 | q |
| 15 | H11 L8 | Emil Tahirovič | Slovenia | 1:02.14 | q |
| 16 | H09 L4 | Domenico Fioravanti | Italy | 1:02.28 | q |
| 17 | H13 L6 | Károly Güttler | Hungary | 1:02.35 | |
| 18 | H11 L6 | Richárd Bodor | Hungary | 1:02.37 | |
| 19 | H10 L5 | Morten Nystrøm | Norway | 1:02.50 | |
| 20 | H12 L7 | Reiner Schneider | Germany | 1:02.54 | |
| 21 | H12 L6 | Dmitry Komornikov | Russia | 1:02.57 | |
| 22 | H09 L8 | Daniel Málek | Czech Republic | 1:02.78 | |
| 23 | H10 L4 | Eduardo Fischer | Brazil | 1:02.80 | |
| 24 | H09 L7 | Davide Rummolo | Italy | 1:02.82 | |
| 25 | H11 L7 | Regan Harrison | Australia | 1:02.84 | |
| 26 | H10 L1 | Remo Lütolf | Switzerland | 1:02.86 | |
| 27 | H13 L2 | Thijs van Valkengoed | Netherlands | 1:02.95 | |
| 28 | H10 L8 | Maxim Podoprigora | Austria | 1:02.97 | |
| 29 | H08 L5 | Sofiane Daid | Algeria | 1:03.01 | |
| 30 | H10 L2 | Mladen Tepavčević | FR Yugoslavia | 1:03.09 | |
| 31 | H08 L4 | Jakob Sveinsson | Iceland | 1:03.11 | |
| 32 | H09 L5 | Chris Stewart | South Africa | 1:03.12 | |
| 33 | H13 L1 | Vlad Polyakov | Kazakhstan | 1:03.19 | |
| 34 | H08 L3 | Valeriy Dymo | Ukraine | 1:03.29 | |
| 35 | H09 L6 | Henrique Barbosa | Brazil | 1:03.36 | |
| 36 | H13 L8 | Yohan Bernard | France | 1:03.45 | |
| 37 | H09 L2 | Alwin de Prins | Luxembourg | 1:03.59 | |
| 38 | H12 L8 | Vanja Rogulj | Croatia | 1:03.60 | |
| 39 | H08 L6 | Matjaž Markič | Slovenia | 1:03.65 | |
| 40 | H09 L3 | Malick Fall | Senegal | 1:03.66 | |
| 41 | H10 L6 | Andrew Bree | Ireland | 1:03.73 | |
| 42 | H07 L2 | Christopher Hansen | Norway | 1:03.83 | |
| 43 | H10 L3 | Haibo Wang | China | 1:04.14 | |
| 44 | H08 L7 | Wickus Nienaber | Swaziland | 1:04.22 | |
| 45 | H10 L7 | Qiliang Zeng | China | 1:04.23 | |
| 46 | H07 L3 | Vladimir Labzin | Estonia | 1:04.79 | |
| 47 | H08 L2 | Arsenio López | Puerto Rico | 1:05.23 | |
| 48 | H07 L7 | Raphael Matthew Chua | Philippines | 1:05.35 | |
| 49 | H02 L8 | Francisco Suriano | El Salvador | 1:05.42 | |
| 50 | H06 L4 | Seung Hun You | South Korea | 1:05.58 | |
| 51 | H07 L4 | Álvaro Fortuny | Guatemala | 1:05.71 | |
| 52 | H06 L7 | Ranui Teriipaia | Tahiti | 1:05.88 | |
| 53 | H06 L3 | Jon Oddur Sigurdsson | Iceland | 1:05.91 | |
| 54 | H08 L1 | Oleg Sidorov | Uzbekistan | 1:06.03 | |
| 55 | H06 L5 | Andrei Capitanciuc | Moldova | 1:06.08 | |
| 56 | H07 L5 | Chi Kin Tam | Hong Kong | 1:06.38 | |
| 57 | H06 L6 | Grant Galant | South Africa | 1:07.05 | |
| 58 | H05 L4 | Hocine Haciane | Andorra | 1:07.06 | |
| 59 | H06 L1 | Jean-Luc Razakarivony | Madagascar | 1:07.25 | |
| 59 | H07 L1 | Sergey Voytsekhovich | Uzbekistan | 1:07.25 | |
| 61 | H05 L5 | Santiago Cavanagh | Bolivia | 1:07.89 | |
| 62 | H07 L6 | Ahmed Al-Kudmani | Saudi Arabia | 1:08.14 | |
| 63 | H05 L8 | Nam Nguyen Thanh | Vietnam | 1:08.60 | |
| 64 | H05 L2 | Kevin Hensley | Virgin Islands | 1:08.73 | |
| 65 | H04 L5 | Conrad Francis | Sri Lanka | 1:08.83 | |
| 66 | H05 L3 | Baktash Gheidi | Iran | 1:08.88 | |
| 67 | H05 L7 | Chan Wai Ma | Macau | 1:09.15 | |
| 68 | H06 L8 | Antonio Leon | Paraguay | 1:09.45 | |
| 69 | H04 L6 | Eric Williams | Nigeria | 1:09.66 | |
| 70 | H04 L1 | Chisela Kanchela | Zambia | 1:09.72 | |
| 71 | H06 L2 | Cheuk Lun Li | Hong Kong | 1:09.74 | |
| 72 | H04 L7 | Hei Meng Lao | Macau | 1:10.28 | |
| 73 | H04 L2 | Onan Thom | Guyana | 1:10.51 | |
| 74 | H05 L6 | Marc Dansou | Benin | 1:10.83 | |
| 75 | H03 L4 | Amar Shah | Kenya | 1:11.14 | |
| 76 | H03 L5 | O. Igbekele Ayenuwa | Nigeria | 1:11.31 | |
| 77 | H03 L6 | Joao Matias | Angola | 1:12.64 | |
| 78 | H05 L1 | Jamie Peterkin | Saint Lucia | 1:12.80 | |
| 79 | H04 L4 | Daniel Kang | Guam | 1:13.73 | |
| 80 | H02 L4 | Omar Jasim | Bahrain | 1:15.01 | |
| 81 | H03 L2 | Alice Shrestha | Nepal | 1:16.49 | |
| 82 | H03 L8 | Guvanch Ataniyazov | Turkmenistan | 1:16.99 | |
| 83 | H02 L3 | Peter James Linch | Zambia | 1:18.24 | |
| 84 | H02 L5 | Issam Halawani | Palestine | 1:18.39 | |
| 85 | H04 L8 | Iyad Houseya | Palestine | 1:20.34 | |
| 86 | H01 L3 | Ronald Ying | Guyana | 1:21.41 | |
| 87 | H04 L3 | Ganzi Mugula | Uganda | 1:21.76 | |
| 88 | H02 L6 | Stephenson Wallace | Saint Vincent and the Grenadines | 1:23.56 | |
| 89 | H02 L2 | Donnie Defreitas | Saint Vincent and the Grenadines | 1:24.51 | |
| 90 | H02 L1 | Lamine Alhousseini | Niger | 1:26.21 | |
| 91 | H02 L7 | Dawson Grace | Samoa | 1:27.16 | |
| 92 | H01 L4 | Joshua Marfleet | Samoa | 1:31.59 | |
| – | H03 L1 | Enkhmandakh Khurlee | Mongolia | DQ | |
| – | H08 L8 | Juan José Madrigal | Costa Rica | DQ | |
| – | H12 L2 | Makoto Yamashita | Japan | DQ | |
| – | – | Mihail Alexandrov | Bulgaria | DNS | |
| – | – | Ahmed Ouattara Zie | Ivory Coast | DNS | |
| – | – | Ben Traore | Ivory Coast | DNS | |
| – | – | A.A. Romain Belemtougri | Burkina Faso | DNS | |