Bullying has become the biggest concern among children calling ChildLine Cymru/Wales in the past decade.
The charity fielded more than 20,300 calls on bullying, representing 14 per cent of all calls.
Other problems included physical abuse, family tensions and concern for others, according to the charity's data.
Director Paul Hemming said: "Over the past 10 years, ChildLine Cymru/Wales has comforted and protected more than 150,0000 children in Wales and given information and advice to thousands more. For some children, ChildLine has literally been a lifeline."
The organisation is celebrating 10 years since it launched its Welsh arm in April 1993. It operates counselling centres in Swansea and Rhyl providing bilingual support.
One volunteer counsellor said: "I am a Welsh speaker and sometimes I hear the relief in a child's voice when I ask them if they want to speak in Welsh."