There are more than 100,000 children on waiting lists and the delays are having a serious impact on children's development and overall outcomes, according to the vice president of the Irish Hospitals Consultants Association.
Dr Gabrielle Colleran said that 106,000 children are waiting for treatment, assessment or diagnostic tests.
Eight thousand children are waiting for CTs, ultrasounds or MRIs and this is delaying the diagnosis of conditions including autism, hearing loss and speech problems, she said.
Dr Colleran said that the delays in assessing hearing and speech delays can have a massive impact on a child's development and impact on how these children are socialising and learning in schools.
Speaking on RTÉ's Today with Claire Byrne, she said there are "huge consequences across a lifespan if we let children down at this early stage".
Staff are frustrated and demoralised seeing the negative impact of delayed access on the delivery of care, she added.
Dr Colleran said that "those of us on the sticky edge of the wedge ... and seeing the impact of the lack of capacity want to see processes and resources in place so that every child and adult gets [care] in a timely fashion, in less than six weeks".
She said: "We just have to do better."
She said one pre-teen referred to her with a neurological condition had been offered an appointment for 2035.
Dr Colleran said "that kind of delay is just farcical ... it is worse for parents and families, but there is huge frustration".
She added that there is "so much talk but we are lacking the action to implement the solutions, they are all the same, we need the right staff and beds to provide timely care".
Shannon-based GP Dr Yvonne Williams said the Government does not seem to have the will and the financial backing to fix the issue of children's waiting lists.
Speaking on the same programme, she said a lot of children missed their development checks in their early stages of their lives.
She said "unfortunately, the children who are most vulnerable are the ones who are most likely to have a delayed diagnosis".
She said locally they are catching up on the development checks, but the dates of those checks have been moved out by a couple of months.
Dr Williams said "the checks that were happening at seven months aren't scheduled to happen now until a baby is 9-11 months. The checks that would have been happening a three-year-old child are now pushed out until that child is nearly four."
She said as a result they are dealing with a lot of delayed diagnoses, particular for autism and disabilities.
She said: "It's very hard to know if your three-year-old is ignoring you because they're busy playing a game and they're having fun, or whether there's actually a problem there. Hearing is so crucial for speech and for development and for social skills that go with that."
Dr Williams said the ear, nose and throat waiting lists are "really long" and it is "really shocking that children have to wait so long if they need treatment for a hearing problem as well".