It has been revealed more than 6,300 children were waiting for a psychology appointment at the end of August.
New HSE figures released to Fianna Fail also show that of that number, over 1,600 were waiting for more than a year.
The party has hit out at the government over the lengthy appointment lists facing children and young people.
Mental Health Spokesperson James Browne says such shortcomings in mental health services for children cannot be allowed to continue.
"This is deeply worrying information especially when we know of the importance of early intervention, especially for children, in and around mental health issues.
"These delays are not only isolated in child mental health services but are actually systemic and persistent across child mental health services.
"We need to see action in this area because it's simply going on for way too long."