The men's 400 metres hurdles event at the 2003 European Athletics U23 Championships was held in Bydgoszcz, Poland, at Zawisza Stadion on 17, 18, and 19 July.
| Gold | Marek Plawgo | |
| Silver | Christian Duma | |
| Bronze | Thomas Kortbeek |
19 July
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| align=left | align=left | | 48.45 | CR | |||
| align=left | align=left | 49.53 | |||||
| align=left | align=left | 49.68 | |||||
| 4 | align=left | align=left |  | 49.90 | |||
| 5 | align=left | align=left | | 50.09 | |||
| 6 | align=left | align=left |  | 50.28 | |||
| 7 | align=left | align=left |  | 50.52 | |||
| 8 | align=left | align=left | | 50.91 |
18 July
Qualified: first 4 in each to the Final
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | | 49.80 | Q | ||
| 2 | align=left | align=left | | 50.24 | Q | ||
| 3 | align=left | align=left | | 50.56 | Q | ||
| 4 | align=left | align=left | | 51.00 | Q | ||
| 5 | align=left | align=left | 51.29 | ||||
| 6 | align=left | align=left |  | 51.59 | |||
| 7 | align=left | align=left | 51.61 | ||||
| 8 | align=left | align=left |  | 116.97 |
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | 49.73 | Q | |||
| 2 | align=left | align=left | | 50.15 | Q | ||
| 3 | align=left | align=left | | 50.20 | Q | ||
| 4 | align=left | align=left | 50.36 | Q | |||
| 5 | align=left | align=left | | 51.22 | |||
| 6 | align=left | align=left | | 51.31 | |||
| 7 | align=left | align=left |  | 51.52 | |||
| 8 | align=left | align=left |  | 52.76 |
17 July
Qualified: first 3 in each heat and 4 best to the Semifinal
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | 50.76 | Q | |||
| 2 | align=left | align=left | | 51.00 | Q | ||
| 3 | align=left | align=left | | 51.21 | Q | ||
| 4 | align=left | align=left | | 51.64 | q | ||
| 5 | align=left | align=left |  | 52.42 | |||
| 6 | align=left | align=left |  | 53.89 |
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | | 50.46 | Q | ||
| 2 | align=left | align=left | | 50.61 | Q | ||
| 3 | align=left | align=left | 51.09 | Q | |||
| 4 | align=left | align=left | | 51.17 | q | ||
| 5 | align=left | align=left | 51.74 | q | |||
| 6 | align=left | align=left | | 51.74 | |||
| 7 | align=left | align=left |  | 53.78 |
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | | 51.00 | Q | ||
| 2 | align=left | align=left | | 51.24 | Q | ||
| 3 | align=left | align=left | | 52.05 | Q | ||
| 4 | align=left | align=left | | 52.40 | |||
| 5 | align=left | align=left |  | 52.45 | |||
| 6 | align=left | align=left | 56.41 |
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | 50.69 | Q | |||
| 2 | align=left | align=left | | 51.39 | Q | ||
| 3 | align=left | align=left | | 51.46 | Q | ||
| 4 | align=left | align=left | | 51.69 | q | ||
| 5 | align=left | align=left | | 51.84 | |||
| 6 | align=left | align=left |  | 52.65 |
According to an unofficial count, 25 athletes from 16 countries participated in the event.
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