Emily Pridham was sent home from Mount Alvernia College yesterday and will not be allowed back until her hair regrows after she shaved it off as part of a cancer research fundraiser on Saturday.

The Catholic girls' school has cited its dress code policy for the temporary ban.

Emily's mother Barbara Pridham said she was "gobsmacked" at the school's punishment and said the family had been given no warning about the possible consequences.

She told ABC radio her daughter had made the decision to part with her locks as a way to cope with her father's battle with leukemia.

"I understand that school rules have to be abided by. However, I've gone through the school rules and the uniform policy and nowhere does it say that a girl cannot shave her head," Ms Pridham said.

"At no stage did [the school] contact me or tell me. At no stage did I think I needed their permission for Emily to do this.

"I am absolutely gobsmacked that this can happen for the reason that it has happened."

A Facebook group supporting Emily's decision to shave her head has appeared, with members calling the school's decision a 'joke' and an 'absolute disgrace'.

Emily's mother said her daughter had decided to take part in the fund-raising head shave as a way of coping with her dad's illness.

"Ten months ago he was given six months to live and we had to explain all of this to Emily," she said.

"I didn't want her to do it. She had beautiful, long blonde hair halfway down her back and I told her she might regret it because she can't just stick it back on ... but she's just been so determined to do it."

The school has defended its actions to enforce uniform guidelines and has said other, "ongoing issues" were behind the suspension.

But Ms Pridham said the only trouble her daughter had been involved in included a warning over nail polish after the school formal two weeks ago and her use of a rude word in the presence of a teacher.

She said her husband, who has undergone a bone marrow transplant, was supportive of Emily's decision to go bald.

"He is very proud of her as everybody that knows her is," Ms Pridham said.

"He is very angry and worried about the rest of her academic year."

Ms Pridham said she had been in contact with the school about the suspension order.