Nearly 250 children have been waiting at least two years to see a speech and language therapist. While another 438 are on the list for more than 12 months.
Speech and language therapy provides treatment for people who have difficulties with communication, eating, drinking and swallowing.
According to details released under the Freedom of Information Act, more than 11,300 children are waiting for an initial assessment.
381 children in the HSE's CHO 7 have been waiting for at least a year, this area includes parts of Dublin, Kildare and west Wicklow. 150 of these children have been waiting for more than two years.
Suzanne Connolly, from Barnardos, says the figures are a huge concern.
"The problem is that children can't wait and that if they don't get the service they need at the right time it will really affect their development and then their long term future developmentally."
A further 889 children have been waiting at least a year for their first speech and language therapy appointment, after an initial assessment.
200 of these have been waiting at least 18 months.