The women's 100 metre backstroke was a swimming event held as part of the swimming at the 1928 Summer Olympics programme.

The competition was held on Thursday and Saturday, 9 and 11 August 1928.

Twelve swimmers from seven nations competed.

In the first heat Ellen King equalized the world record with 1:22.0 minutes.

In the second heat Marie Braun bettered the world record to 1:21.6 minutes.