2010 World Junior Championships in Athletics – Women's 400 metres

22 July

Rank	Name	Nationality	Time	Notes
	Shaunae Miller	Bahamas	52.52
	Margaret Etim	Nigeria	53.05
	Bianca Răzor	Romania	53.17
4	Stacey-Ann Smith	United States	53.42
5	Jody-Ann Muir	Jamaica	53.42
6	Bukola Abogunloko	Nigeria	53.74
7	Regina George	United States	53.83
8	Chantel Malone	British Virgin Islands	53.91

21 July

Rank	Name	Nationality	Time	Notes
1	Bukola Abogunloko	Nigeria	52.86	Q
2	Bianca Răzor	Romania	53.06	Q
3	Jody-Ann Muir	Jamaica	53.20	q
4	Regina George	United States	53.59	q
5	Anneliese Rubie	Australia	54.39
6	Gulustan Mahmood	Iraq	54.70
7	Christina Zwirner	Germany	54.86
8	Miho Shingu	Japan	55.66

Rank	Name	Nationality	Time	Notes
1	Margaret Etim	Nigeria	52.63	Q
2	Shaunae Miller	Bahamas	53.21	Q
3	Bárbara de Oliveira	Brazil	53.60
4	Ella Räsänen	Finland	53.73
5	Katherine Reid	Canada	53.80
6	Sade Sealy	Barbados	54.90
7	Julia Schaefers	Germany	55.09
	Yuliya Yurenia	Belarus	DQ	IAAF rule 162.7

Rank	Name	Nationality	Time	Notes
1	Chantel Malone	British Virgin Islands	53.37	Q
2	Stacey-Ann Smith	United States	53.48	Q
3	Chanice Chase	Canada	53.72
4	Maria Lebedeva	Russia	53.86
5	Rashan Brown	Bahamas	54.14
6	Adelina Pastor	Romania	54.47
7	Janieve Russell	Jamaica	55.16
8	Marta Maffioletti	Italy	55.72

20 July

Rank	Name	Nationality	Time	Notes
1	Maria Lebedeva	Russia	54.02	Q
2	Regina George	United States	54.17	Q
3	Janieve Russell	Jamaica	54.65	Q
4	Yuliya Yurenia	Belarus	54.67	Q
5	Rashan Brown	Bahamas	54.85	q
6	Sandra Wagner	Sweden	55.28
7	Shawna Fermin	Trinidad and Tobago	55.50
8	Romana Tea Kirinic	Croatia	56.27

Rank	Name	Nationality	Time	Notes
1	Bukola Abogunloko	Nigeria	53.38	Q
2	Stacey-Ann Smith	United States	53.41	Q
3	Chanice Chase	Canada	53.61	Q
4	Adelina Pastor	Romania	53.74	Q
5	Christina Zwirner	Germany	54.57	q
6	Deseree King	U.S. Virgin Islands	56.73
7	Hristina Risteska	North Macedonia	58.80
8	Kristie Baillie	New Zealand	59.98

Rank	Name	Nationality	Time	Notes
1	Shaunae Miller	Bahamas	52.45	Q
2	Margaret Etim	Nigeria	52.48	Q
3	Ella Räsänen	Finland	53.87	Q
4	Anneliese Rubie	Australia	54.29	Q
5	Miho Shingu	Japan	54.79	q
6	Liona Rebernik	Slovenia	55.60
7	Ashley Kelly	British Virgin Islands	55.71

Rank	Name	Nationality	Time	Notes
1	Chantel Malone	British Virgin Islands	52.97	Q
2	Bárbara de Oliveira	Brazil	53.35	Q
3	Katherine Reid	Canada	54.48	Q
4	Marta Maffioletti	Italy	54.98	Q
5	Sparkle McKnight	Trinidad and Tobago	55.01
6	Liliana Núñez	Ecuador	56.30
7	Kanika Beckles	Grenada	58.95

Rank	Name	Nationality	Time	Notes
1	Jody-Ann Muir	Jamaica	53.83	Q
2	Bianca Răzor	Romania	53.85	Q
3	Gulustan Mahmood	Iraq	54.62	Q
4	Julia Schaefers	Germany	54.65	Q
5	Sade Sealy	Barbados	54.88	q
6	Elin Moraiti	Sweden	55.95
7	Malama Dosso	France	56.40
8	Francesca Xuereb	Malta	56.61

According to an unofficial count, 38 athletes from 28 countries participated in the event.