Nearly 5,300 children have not been allocated a social worker by Tusla - despite child protection and welfare concerns.
Over 680 are deemed high priority cases.
Areas of Dublin have the longest lists, followed by the midwest, Waterford/Wexford and Donegal.
Joseph Mooney, assistant professor of social work in UCD, says staffing issues are causing the long waiting lists.
"I would out a large proportion of that down to resources, which Tusla and social work across the board have been struggling with for years now.
"There is an immediate screening process, there are community resources that are possibly linked in with several of those cases, and what I mean by that is they're not child protection allocated social workers, but they could be community family support services that are checking and linking in with those scenarios."
