| | Event type
400 metres, Girls
| Date | 11 – 14 October 2018 | |
|---|---|---|
| Status | YOG | |
| Location | Athletics Field, Parque Olímpico de la Juventud, Villa Soldati, Buenos Aires | |
| Participants | 25 from 25 countries | |
| Format | Two stages with final results determined by cumulative time. | |
| Pos | Competitor | NOC | Time | |||
|---|---|---|---|---|---|---|
| 1 | Barbora Malíková |  CZE | 1:48.86 | Gold | ||
| 2 | Marie Scheppan |  GER | 1:50.06 | Silver | ||
| 3 | Niddy Mingilishi |  ZAM | 1:50.48 | Bronze | ||
| 4 | Erica Cavalheiro |  BRA | 1:51.03 | |||
| 5 | Liefde Schoemaker |  BEL | 1:51.89 | |||
| 6 | Alina Luchshava |  BLR | 1:51.90 | |||
| 7 | Janka Molnár |  HUN | 1:51.93 | |||
| 8 | Andrea Jiménez |  ESP | 1:52.14 | |||
| 9 | Meghan Hunter |  USA | 1:52.91 | |||
| 10 | Favour Ofili |  NGR | 1:53.02 | |||
| 11 | Deshana Skeete |  GUY | 1:53.57 | |||
| 12 | Lorena Rangel |  MEX | 1:53.94 | |||
| 13 | Ola Buwaro |  GAM | 1:55.00 | |||
| 14 | Jasneet Nijjar |  CAN | 1:55.72 | |||
| 15 | Nataliya Dyshliuk |  UKR | 1:55.73 | |||
| 16 | Aleksandra Zalyubovskaya |  KAZ | 1:55.76 | |||
| 17 | Ana Costa |  POR | 1:56.30 | |||
| 18 | Kinga Gacka |  POL | 1:56.57 | |||
| 19 | Wang You-Hsuan |  TPE | 1:57.66 | |||
| 20 | Adina Cîrciogel |  ROU | 1:57.82 | |||
| 21 | Serenia Ragatu |  FIJ | 2:02.92 | |||
| Daniella Deer |  JAM | – | ||||
| Megan Moss |  BAH | – | ||||
| Jiijo Hassan Mohamed |  SOM | – | ||||
| Aissata Denn Conte |  GUI | – |