133 children under the age of 16 had inpatient admissions in acute hospitals due to eating disorders last year.
According to freedom of information figures, 104 of them were hospitalised with anorexia.
The HSE says this illness has the highest death rate of all mental health disorders, and is rising among adolescents.
In the Saolta hospital group, which operates public hospitals in the West and Northwest, 38 children were admitted last year - mostly for anorexia.
This was down on 59 admissions the previous year.
Harriet Parsons is from Bodywhys, the Eating Disorders Association of Ireland says the new figures are very concerning.