An 11-year-old girl with a nose stud may be expelled from her school because her piercing is against the rules.
Avonbourne School in Bournemouth says visible piercings are banned, and is forcing Jessica Wilkins to work in isolation until she removes the stud.
But Jessica has refused even though she knows she may be expelled.
Her mother Samantha, who allowed Jessica to have the piercing as a Christmas present, said the school was being unreasonable.
Mrs Wilkins told BBC News: "She's not going to change because she has a nose piercing.
"She's not suddenly going to come out with an attitude or start treating people differently just because she has a nose piercing.
"She's still the same person, she's still going to do the same things at school so I really, really don't understand why they have this policy."
Head teacher Pauline Greaves said it was "the thin end of the wedge".
"If we don't enforce the rules that we have - we'll have an anarchic situation.
"We want this child back into school; we want to continue Jessica's education.
"I think the responsibility for that happening lies with the parent - the parent knew the rules before she took the child along to have the piercing done."
Ms Greaves said parents who disagreed should write to the governors.