The women's 400 metres at the 2016 IAAF World Indoor Championships took place on March 18 and 19, 2016.

[1][2] Nigerian born Oluwakemi Adekoya, a mercenary runner for Bahrain,[3] came into these championships as only the seventh fastest in the world this year, but she made her mark with the fastest times in each round.

Hayes gathered herself and made one big push coming around the final turn, but Adekoya was able to hold her off.

Hayes tried again coming off the turn but couldn't make any progress.

As Hayes strained for the finish, she made a second strategic mistake and allowed Ashley Spencer to pass on her inside, Spencer pipping her for the silver medal at the line.