St Mary's Diocesan School for Girls is a private boarding and day school for girls situated on St Marys Road in the suburb of Kloof (eThekwini Metropolitan Municipality), near Durban, in KwaZulu-Natal, South Africa.

The school was founded in 1906 on Field's Hill in the small town of Kloof and was called St Elizabeth's Diocesan School for Girls.

It relocated to its present site in 1909 and was renamed St Mary's Diocesan School for Girls in 1919 at the stipulation of a benefactor.

The school has an Anglican foundation, and students attend chapel a few mornings a week.

The school ground covers 12 hectares (30 acres).