The abuse over three decades included the girls being slapped, kicked, punched, dragged by the hair, isolated for weeks and raped with a broomstick.
The royal commission into child sexual abuse is hearing the experiences of 16 women who were inmates at Parramatta Girls home between 1950 and 1974 and at the Hay Institution for Girls, a maximum security annex for inmates who were rebellious and difficult.
Counsel assisting the commission Caroline Spruce said the experiences of the women are similar.
They tell of physical abuse by officers, resulting in serious injuries as they tried to defend themselves from being raped.
Some were also subdued with the drug Largactil, used to treat severe depression and behavioural disturbances, before being raped.
They were also held in isolation cells for long periods of time with straw bedding and fed on bread and water.
Robin Kitson, who was committed to Parramatta Girls twice, told how she was kicked, punched and dragged by the hair. Her nose was held and Largactil was poured down her throat.
When she went back on the second occasion, "I had all my teeth forcibly removed by the dentist because they said I was a bad girl. I was 16."
Ms Kitson, now 66, said she came from a big Irish/Aboriginal family who lived at Broken Hill and then Ivanhoe.
She was first picked up after she ran away from home to see her grandmother.
During her incarceration at Parramatta she was raped by other girls. Two held her down and sexually assaulted her with a broomstick.
A welfare officer to whom she told about the abuse reported it to Percival Edward Mayhew who was superintendent at the time, and he "smashed her in the face with a bunch of keys".
She ended up in isolation for 21 days. Mayhew, who is now dead, is one of 10 former officers against whom allegations have been made.
The institutions closed in the mid-70s after public outcry and protests.
The NSW government, which is represented at the hearing, is not disputing the allegations and will give evidence of major reforms.
The hearing continues.
