The women's 400 metres event at the 1996 World Junior Championships in Athletics was held in Sydney, Australia, at International Athletic Centre on 21, 22 and 23 August.
| Gold | Andrea Burlacu | |
| Silver | Suziann Reid | |
| Bronze | Rosemary Hayward |
23 August
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| align=left | align=left | | 52.32 | ||||
| align=left | align=left | | 53.17 | ||||
| align=left | align=left | | 53.28 | ||||
| 4 | align=left | align=left |  | 53.43 | |||
| 5 | align=left | align=left |  | 53.45 | |||
| 6 | align=left | align=left | | 53.87 | |||
| 7 | align=left | align=left | 54.46 | ||||
| 8 | align=left | align=left |  | 54.61 |
22 August
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | | 53.05 | Q | ||
| 2 | align=left | align=left | | 53.11 | Q | ||
| 3 | align=left | align=left | 53.86 | Q | |||
| 4 | align=left | align=left | | 53.95 | Q | ||
| 5 | align=left | align=left | | 54.55 | |||
| 6 | align=left | align=left |  | 55.07 | |||
| 7 | align=left | align=left |  | 55.24 | |||
| 8 | align=left | align=left |  | 56.30 |
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | | 53.60 | Q | ||
| 2 | align=left | align=left | | 53.70 | Q | ||
| 3 | align=left | align=left | | 53.89 | Q | ||
| 4 | align=left | align=left | | 53.98 | Q | ||
| 5 | align=left | align=left |  | 54.52 | |||
| 6 | align=left | align=left |  | 55.38 | |||
| 7 | align=left | align=left | | 55.79 | |||
| align=left | align=left | | DNS |
21 August
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | 54.09 | Q | |||
| 2 | align=left | align=left | | 54.14 | Q | ||
| 3 | align=left | align=left | | 54.56 | Q | ||
| 4 | align=left | align=left | | 55.64 | q | ||
| 5 | align=left | align=left | | 56.40 | q | ||
| 6 | align=left | align=left | 59.30 | ||||
| 7 | align=left | align=left |  | 60.04 |
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | | 53.88 | Q | ||
| 2 | align=left | align=left | | 54.39 | Q | ||
| 3 | align=left | align=left | | 54.94 | Q | ||
| 4 | align=left | align=left | 57.37 | ||||
| 5 | align=left | align=left | | 58.11 | |||
| 6 | align=left | align=left | 59.09 |
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | | 53.98 | Q | ||
| 2 | align=left | align=left | | 54.04 | Q | ||
| 3 | align=left | align=left | | 54.34 | Q | ||
| 4 | align=left | align=left | | 56.54 | q | ||
| 5 | align=left | align=left | 59.00 |
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | | 54.00 | Q | ||
| 2 | align=left | align=left | | 54.71 | Q | ||
| 3 | align=left | align=left | | 54.83 | Q | ||
| 4 | align=left | align=left | | 55.89 | q | ||
| 5 | align=left | align=left | 56.91 | ||||
| 6 | align=left | align=left |  | 59.14 |
According to an unofficial count, 24 athletes from 19 countries participated in the event.