An intoxicated primary school youngster was among dozens of children admitted to the accident and emergency unit at a Hull hospital, a report has found.
Research into the drinking habits of young people in the port found 166 people under 18 attended casualty in 2007 with drink-related problems.
Hull's Citysafe organisation said doctors dealing with those cases recorded "acute alcohol intoxication".
Citysafe said they now better understood the severity of the problem.
Citysafe noted the youngest person to arrive at hospital was six but the report's authors stressed this could have been a case of accidental consumption.
A total of 480 young people were questioned about their drinking habits by officers dealing with anti-social behaviour, along with drug and alcohol workers.
The survey also found that 95% of all those questioned were drinking alcohol at a level regarded as harmful and more than a fifth of young people may have a serious alcohol dependence.
Kate Stevenson, alcohol project manager from Hull Citysafe, said: "The results from this study are concerning, but it will help us address the issue of alcohol misuse with young people much more effectively as we now understand the severity of the problem."
She said the majority of the young people questioned were not buying alcohol themselves, but were asking family members or strangers to buy alcohol for them.