The women's 400 metres hurdles event at the 1986 World Junior Championships in Athletics was held in Athens, Greece, at Olympic Stadium on 16, 17 and 18 July.
| Gold | Claudia Bartl | |
| Silver | Kellie Roberts | |
| Bronze | Svetlana Lukashevich |
18 July
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| align=left | align=left | 56.76 | |||||
| align=left | align=left | | 56.80 | ||||
| align=left | align=left | 57.92 | |||||
| 4 | align=left | align=left |  | 58.00 | |||
| 5 | align=left | align=left |  | 58.74 | |||
| 6 | align=left | align=left | | 58.80 | |||
| 7 | align=left | align=left | 60.32 | ||||
| 8 | align=left | align=left | 61.14 |
17 July
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | | 57.86 | Q | ||
| 2 | align=left | align=left | | 58.27 | Q | ||
| 3 | align=left | align=left | 59.25 | Q | |||
| 4 | align=left | align=left | | 59.60 | Q | ||
| 5 | align=left | align=left | 60.29 | ||||
| 6 | align=left | align=left | 61.40 | ||||
| 7 | align=left | align=left |  | 63.13 | |||
| 8 | align=left | align=left | 63.85 |
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | 58.23 | Q | |||
| 2 | align=left | align=left | 59.06 | Q | |||
| 3 | align=left | align=left | | 59.84 | Q | ||
| 4 | align=left | align=left | 61.19 | Q | |||
| 5 | align=left | align=left |  | 61.97 | |||
| 6 | align=left | align=left |  | 62.21 | |||
| 7 | align=left | align=left |  | 62.38 | |||
| align=left | align=left | DNS |
16 July
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | 57.90 | Q | |||
| 2 | align=left | align=left | 58.50 | Q | |||
| 3 | align=left | align=left | | 60.75 | Q | ||
| 4 | align=left | align=left | 61.53 | Q | |||
| 5 | align=left | align=left | | 62.40 | q | ||
| 6 | align=left | align=left | | 62.94 | q | ||
| 7 | align=left | align=left |  | 66.82 |
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | | 60.12 | Q | ||
| 2 | align=left | align=left | 60.64 | Q | |||
| 3 | align=left | align=left | 60.86 | Q | |||
| 4 | align=left | align=left | 60.89 | Q | |||
| 5 | align=left | align=left | 64.86 | q | |||
| 6 | align=left | align=left | | 66.03 | |||
| 7 | align=left | align=left |  | 66.88 |
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | | 57.54 | Q | ||
| 2 | align=left | align=left | | 58.94 | Q | ||
| 3 | align=left | align=left | 61.20 | Q | |||
| 4 | align=left | align=left | | 61.36 | Q | ||
| 5 | align=left | align=left | | 63.84 | q | ||
| 6 | align=left | align=left | 66.00 | ||||
| 7 | align=left | align=left | 66.80 |
According to an unofficial count, 21 athletes from 17 countries participated in the event.