The women's 400 metres hurdles event at the 1988 World Junior Championships in Athletics was held in Sudbury, Ontario, Canada, at Laurentian University Stadium on 27, 28 and 29 July.
| Gold | Antje Axmann | |
| Silver | Ann Maenhout | |
| Bronze | Silvia Rieger |
29 July
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| align=left | align=left | 57.47 | |||||
| align=left | align=left | | 57.58 | ||||
| align=left | align=left | 57.88 | |||||
| 4 | align=left | align=left |  | 58.71 | |||
| 5 | align=left | align=left |  | 58.79 | |||
| 6 | align=left | align=left | 58.99 | ||||
| 7 | align=left | align=left | 59.07 | ||||
| 8 | align=left | align=left | 59.25 |
28 July
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | 57.69 | Q | |||
| 2 | align=left | align=left | 57.84 | Q | |||
| 3 | align=left | align=left | | 58.41 | Q | ||
| 4 | align=left | align=left | | 59.96 | q | ||
| 5 | align=left | align=left | 60.06 | ||||
| 6 | align=left | align=left |  | 60.17 | |||
| 7 | align=left | align=left |  | 60.18 | |||
| align=left | align=left |  | DQ |
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | | 58.71 | Q | ||
| 2 | align=left | align=left | 59.07 | Q | |||
| 3 | align=left | align=left | 59.52 | Q | |||
| 4 | align=left | align=left | 60.01 | q | |||
| 5 | align=left | align=left | | 60.39 | |||
| 6 | align=left | align=left |  | 62.87 | |||
| align=left | align=left |  | DNF | ||||
| align=left | align=left | DNF |
27 July
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | | 59.51 | Q | ||
| 2 | align=left | align=left | | 59.54 | Q | ||
| 3 | align=left | align=left |  | 61.10 | |||
| 4 | align=left | align=left |  | 61.85 | |||
| 5 | align=left | align=left |  | 61.98 | |||
| 6 | align=left | align=left |  | 63.21 | |||
| 7 | align=left | align=left | 63.61 |
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | 59.36 | Q | |||
| 2 | align=left | align=left | 59.59 | Q | |||
| 3 | align=left | align=left | 60.37 | q | |||
| 4 | align=left | align=left | | 60.55 | q | ||
| 5 | align=left | align=left |  | 60.69 | |||
| 6 | align=left | align=left |  | 62.07 | |||
| 7 | align=left | align=left | 63.65 |
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | 59.28 | Q | |||
| 2 | align=left | align=left | | 59.90 | Q | ||
| 3 | align=left | align=left | | 60.05 | q | ||
| 4 | align=left | align=left | 60.78 | ||||
| 5 | align=left | align=left | 61.89 | ||||
| 6 | align=left | align=left | | 62.00 | |||
| align=left | align=left | DNF |
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | 59.59 | Q | |||
| 2 | align=left | align=left | | 59.71 | Q | ||
| 3 | align=left | align=left | | 59.73 | q | ||
| 4 | align=left | align=left |  | 61.05 | |||
| 5 | align=left | align=left | | 61.36 | |||
| 6 | align=left | align=left | | 62.05 | |||
| 7 | align=left | align=left | | 62.82 |
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | 59.23 | Q | |||
| 2 | align=left | align=left | 59.28 | Q | |||
| 3 | align=left | align=left | | 59.30 | q | ||
| 4 | align=left | align=left | | 59.65 | q | ||
| 5 | align=left | align=left | | 61.99 | |||
| 6 | align=left | align=left |  | 62.00 | |||
| 7 | align=left | align=left | | 63.54 |
According to an unofficial count, 35 athletes from 25 countries participated in the event.