A hospital accident and emergency unit treated 34 children injured by bullies in one school term, it has emerged.
In the study at Morriston Hospital, 21 of the 34 victims were boys
Most were bullied at school, with some forced to take drugs or drug overdoses and others suffered broken bones, bruises or cuts.
The research carried out by consultants at Morriston Hospital, Swansea, in 1999 has only recently been made public.
The head of the expert team said it offered an accurate glimpse of the bullying problem across the UK.
The study showing that an average three children a week were being dealt with in hospital was detailed at a European regional conference on child abuse last summer.
The research was led by consultant community paediatrician Alison Maddocks, fellow paediatrician Lorna Price and Morriston Hospital A&E consultant Mike McCabe.
Dr Maddocks presented her findings to a European regional conference on child abuse in Berlin.
The same team is preparing to carry out a comparative study in an effort to gauge whether the problem has improved.
MORRISTON A&E RESEARCH
Over 60% of attacks were in school
15% of injuries involved a bone fracture
25% of injuries were cuts and abrasions
"I cannot say that these results would be unique to the Swansea area," said Dr Maddocks. "We decided to do the research because there was a feeling that some of the children seen at the A&E unit had injuries that might result from bullying.
"Posters were put up at the A&E asking people to report whether an injury was as a result of bullying.
"One of the facts that came out of the research is that injuries from bullying are not as the result of accidents, they are done on purpose.
"Now we are looking at doing a comparative study to see whether things have improved. It would have to be done in the summer like the last one."
The earlier study focused on the greater Swansea area with an estimated population of 365,000 people.
They included 66,000 children, any of whom could have potentially used the A&E unit over the period.
Bullying is a blight on the lives of thousands of schoolchildren
Of the 34 victims, 21 were boys and 13 girls. The youngest was four, and the oldest 15.
The head, face, hands and arms were the most commonly abused areas, with hitting and punching the most common method of attack.
In three cases children were jumped or stamped on, two were thrown and two were butted. There were two overdoses and one case of drug abuse.
Dr Maddocks said children frequently bullied at school were more likely to wet their beds, they could have difficulty sleeping and suffer headaches as well as a range of psychological problems including anxiety and depression.
She said experts in Berlin who heard her findings were interested, but she added: "It is something that is very topical but sadly I do not think that it is very shocking, wherever you are from."