There are not large numbers of children ringing the line. But Anne Houston, ChildLine's director, says that "a significant number" do phone up to talk about sexual abuse.
The dedicated line is advertised in places where young people live away from home, and it takes up to 100 calls a month. About 20 callers are actually counselled.
Mrs Houston says perhaps 10 or 15 of the 100 calls are about sexual abuse. Callers are predominantly male, and some of them say they are being abused by their peers.
Young people who have been abused come into care or residential schools only to fall victims to abuse by staff, according to Mrs Houston. Anyone from cleaners to care staff may prey on them, she says.
"These young people have an appalling lack of self-esteem. Very often they won't complain because they believe they won't be taken seriously, and very often they do not want to be put out of where they're living. They always describe how vulnerable they feel.
"Some are abused on home visits but do not want the visits to stop. It can be the only affection they get," says Mrs Houston.
Several callers a month make repeated attempts to contact ChildLine. Many young people are so confused about their situation they are no longer clear about what constitutes appropriate relationships, says Mrs Houston.
A survey last year by the Centre for Residential Child Care at Strathclyde University found that staff in two-thirds of all residential establishments in Scotland believe the children they care for have been abused. Staff in one third of establishments also say they are caring for children who have sexually abused others.
The survey concluded that abuse is a "frequent and serious" problem.