The women's 400 metres hurdles event at the 2008 World Junior Championships in Athletics was held in Bydgoszcz, Poland, at Zawisza Stadium on 9, 10 and 11 July.
| Gold | Takecia Jameson | |
| Silver | Janeil Bellille | |
| Bronze | Meghan Beesley |
11 July
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| align=left | align=left | | 56.29 | ||||
| align=left | align=left | 56.84 | |||||
| align=left | align=left | 57.08 | |||||
| 4 | align=left | align=left |  | 57.22 | |||
| 5 | align=left | align=left | 57.46 | ||||
| 6 | align=left | align=left | | 58.43 | |||
| 7 | align=left | align=left |  | 58.62 | |||
| 8 | align=left | align=left |  | 59.05 |
10 July
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | 57.24 | Q | |||
| 2 | align=left | align=left | 57.54 | Q | |||
| 3 | align=left | align=left | | 57.84 | Q | ||
| 4 | align=left | align=left | | 58.00 | q | ||
| 5 | align=left | align=left |  | 58.21 | |||
| 6 | align=left | align=left | 58.22 | ||||
| 7 | align=left | align=left |  | 59.16 | |||
| 8 | align=left | align=left | 60.39 |
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | | 57.31 | Q | ||
| 2 | align=left | align=left | 57.73 | Q | |||
| 3 | align=left | align=left | | 57.86 | Q | ||
| 4 | align=left | align=left | | 58.04 | q | ||
| 5 | align=left | align=left |  | 58.58 | |||
| 6 | align=left | align=left |  | 59.34 | |||
| 7 | align=left | align=left |  | 60.05 | |||
| align=left | align=left | | DNF |
9 July
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | | 59.05 | Q | ||
| 2 | align=left | align=left | 59.51 | Q | |||
| 3 | align=left | align=left | 59.83 | Q | |||
| 4 | align=left | align=left |  | 59.88 | |||
| 5 | align=left | align=left | | 60.59 | |||
| 6 | align=left | align=left |  | 62.16 |
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | | 58.89 | Q | ||
| 2 | align=left | align=left | | 58.95 | Q | ||
| 3 | align=left | align=left | | 59.16 | Q | ||
| 4 | align=left | align=left | | 59.41 | q | ||
| 5 | align=left | align=left |  | 59.97 | |||
| 6 | align=left | align=left |  | 60.13 | |||
| 7 | align=left | align=left | | 61.20 | |||
| 8 | align=left | align=left |  | 61.40 |
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | | 58.81 | Q | ||
| 2 | align=left | align=left | | 59.16 | Q | ||
| 3 | align=left | align=left | 59.20 | Q | |||
| 4 | align=left | align=left |  | 59.97 | |||
| 5 | align=left | align=left | | 60.00 | |||
| 6 | align=left | align=left | 60.61 | ||||
| 7 | align=left | align=left |  | 61.57 |
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | | 57.58 | Q | ||
| 2 | align=left | align=left | 58.40 | Q | |||
| 3 | align=left | align=left | | 58.58 | Q | ||
| 4 | align=left | align=left | | 58.89 | q | ||
| 5 | align=left | align=left | | 59.39 | q | ||
| 6 | align=left | align=left | 59.50 | q | |||
| 7 | align=left | align=left |  | 60.67 | |||
| 8 | align=left | align=left |  | 61.06 |
According to an unofficial count, 29 athletes from 23 countries participated in the event.