| | Event type
4 × 100 metres Medley Relay, Girls
| Date | 8 October 2018 — 19:29 | |
|---|---|---|
| Status | YOG | |
| Location | Natatorium, Parque Olímpico de la Juventud, Villa Soldati, Buenos Aires | |
| Participants | 28 from 7 countries | |
| Format | Final round only. | |
| Pos | Lane | Swimmer | NOC | Time | Exchange (Pos) | |||
|---|---|---|---|---|---|---|---|---|
| 1 | – | People's Republic of China |  CHN | 4:05.18 | Gold | |||
| Peng Xuwei | 1:01.64 | – (–) | ||||||
| Zheng Muyan | 1:10.13 | – (–) | ||||||
| Lin Xintong | 59.42 | – (–) | ||||||
| Yang Junxuan | 53.99 | – (–) | ||||||
| 2 | – | Australia |  AUS | 4:05.46 | Silver | |||
| Kaylee McKeown | 1:01.61 | – (–) | ||||||
| Chelsea Hodges | 1:08.83 | – (–) | ||||||
| Michaela Ryan | 1:00.12 | – (–) | ||||||
| Abbey Webb | 54.90 | – (–) | ||||||
| 3 | – | Russian Federation |  RUS | 4:06.07 | Bronze | |||
| Darya Vaskina | 1:02.74 | – (–) | ||||||
| Anastasiya Makarova | 1:08.63 | – (–) | ||||||
| Polina Yegorova | 59.50 | – (–) | ||||||
| Yelizaveta Klevanovich | 55.20 | – (–) | ||||||
| 4 | – | Brazil |  BRA | 4:10.93 | ||||
| Fernanda de Goeij | 1:02.26 | – (–) | ||||||
| Ana Vieira | 1:12.04 | – (–) | ||||||
| Maria Pessanha | 1:00.63 | – (–) | ||||||
| Rafaela Raurich | 56.00 | – (–) | ||||||
| 5 | – | United States |  USA | 4:16.79 | ||||
| Rhyan White | 1:01.66 | – (–) | ||||||
| Kate Douglass | 1:10.85 | – (–) | ||||||
| Kaitlynn Sims | 1:05.68 | – (–) | ||||||
| Maddie Donohoe | 58.60 | – (–) | ||||||
| 6 | – | South Africa |  RSA | 4:17.78 | ||||
| Mariella Venter | 1:04.12 | – (–) | ||||||
| Christin Mundell | 1:12.05 | – (–) | ||||||
| Duné Coetzee | 1:02.61 | – (–) | ||||||
| Kate Beavon | 59.00 | – (–) | ||||||
| – | Canada |  CAN | – | |||||
| Madison Broad | 1:02.26 | – (–) | ||||||
| Nina Kucheran | 1:10.46 | – (–) | ||||||
| Avery Wiseman | 1:04.03 | – (–) | ||||||
| Kyla Leibel | – | – (–) |