She graduated in 1894 and commenced practice, however, in 1897 she contracted a cold and died at 27 years of age.

O'Hara and her sister Elizabeth wished to become doctors, and passed matriculation at the University of Melbourne, but due to the medicine faculty's ban on women, they began to look into options for study overseas.

[5] Lilian Alexander, and Helen Sexton posted a notice in the newspaper seeking women who wished to enrol in medicine so they could apply as a group.

O'Hara and her Elizabeth applied, as did Grace Vale, Clara Stone, and Margaret Whyte.

[7] O'Hara died on 26 April 1897 at her Beaconsfield parade residence in Albert Park, after having contracted a cold two weeks earlier.