She finished eighth in her heat
Fiona Doyle has missed out on a place in the 100 metres breaststroke semi-finals.
The Irish swimmer finished eighth in a time of 1:07:58 in Heat 5.
Russia's Yulia Efimova won the heat in a time of 1:05:79, 0.93 seconds ahead of Jamaica's Alia Atkinson.
Third place went to Jennie Johansson of Sweden.