Figures show there are over 2,200 children and teenagers waiting for an appointment to see a mental health specialist, with 200 waiting a year or more for services.
The worst affected areas include Kerry and Cork with 162 children waiting over 12 months for an appointment.
Wicklow and parts of Dublin also have high waiting lists.
In a statement, the Health Service Executive said waiting times for young people to be seen by Child and Adolescent Mental Health Services (CAMHS) continue to be an issue in a number of areas.
It said that every effort is made to prioritise urgent referrals so that young people who are deemed as high risk are seen as soon as possible.
The HSE added that this may impact on waiting times for cases that are considered to be less severe.
It also said the CAMHS referral teams meet every week to review all referrals and to assess the risk to the young person, adding that an initiative is under way to improve early intervention for young people with mild mental health difficulties through the employment of 114 new assistant psychologists.
It said 20 psychologists were also recruited as part of this initiative to provide supervision and guidance.
Sinn Féin's Health Spokesperson Louise O 'Reilly said the situation showed the Government's failure to invest in mental health services.
"These children are left to wait and the stress of waiting for a year or more in some cases takes its toll on the whole family.
Ms O’Reilly said targeted investment in frontline services, including mental health, is required if the Government and the HSE are serious about resourcing primary care.
"There are real stories of human pain behind the every one of these figures," she added.