Over 900 children were treated in hospital for drug or alcohol-related illnesses last year.
According to information gathered under the Freedom of Information Figures, nearly two thirds were girls.
The conditions include drug or alcohol poisoning and mental health disorders due to substance misuse,
It also includes new-born children affected by their mothers' use of drugs or alcohol.
914 kids were treated for these conditions last year.
The figures are spread throughout the country, but 28 per cent were treated in children's hospitals.
Dr Ciara Martin - a consultant paediatrician with Children's Health Ireland - says the problem's worse than the figures suggest.
"Its probably the tip of an iceberg".
"We have a lot more 10-17 year olds drinking, he ones who get into trouble are the ones who come into us in hospital".
She described the figures as "very small" and say they "don't represent what's happening".
There 228 kids who were treated for drugs and alcohol illness aged less than nine years old.