A children's charity says a huge shortfall in counselling is leaving thousands of sexually abused young people struggling to recover.
The NSPCC says many services are so overstretched that they are being forced to close their books.
It found fewer than one support programme per 10,000 children in England, Northern Ireland and Scotland.
MP George Galloway has revealed he was abused as a child, as he backed new checks for adults working in schools.
The NSPCC said there were up to 88,500 sex abuse victims across the UK.
The charity's report found that when therapy was available to young victims, there could be a delay of up to a year on waiting lists.
And teenagers were particularly likely to miss out on counselling because they were considered too old for a child protection plan but too young for adult services.
Often therapy was offered too late, when a child was already showing the effects of the abuse, and a gap was identified in provision to deal with rape and sexual abuse.
The NSPCC's Debbie Allnock, who led the research, said there was a need for "huge investment" into therapeutic services for children.
"Sexual abuse can have devastating consequences for a child but it remains a low priority within mainstream mental health services and among local authorities," she said.
She said the abuse often led to "severe long-term behavioural, criminal and addiction problems".
"It takes bravery for a young person to tell someone about their sexual abuse and ask for help.
"But their suffering may only get noticed when they show significant signs of distress, anguish or damaging behaviours. They may then have a long wait for the support they desperately need."
George Galloway revealed he was abused when he was 11, as he backed a scheme to vet everyone who works with children which comes into effect in October.
It has been opposed by leading authors who go into schools, including Philip Pullman, who said the idea was "ludicrous and insulting".
However, writing in the Daily Record, Mr Galloway said the checks would be worth it if they spared a child the "horrors" of sexual abuse.
Referring to child killer Ian Huntley and the Dunblane Primary massacre, he wrote: "Every time a Soham murderer or a Dunblane Thomas Hamilton emerges, I die a little inside as I remember that dirty old man driven by the same perverted interest in sexually attacking kids."
Mr Galloway said he had not even revealed the abuse to his wives.
"All I feel is ashamed, though I was the child victim and he the aggressive predator."
In response to the NSPCC report, a Department of Health spokesman said it had commissioned a report into youth mental health services.
"There have been considerable recent improvements in the delivery and quality of child and adolescent mental health services (CAMHS) due to a 62% increase in spending since 2003-04 and a year-on-year reduction in waiting times," he added.