Nearly 5,000 children, deemed child protection and welfare cases, have not been allocated a social worker.
According to Tusla's latest figures, 722 are regarded as 'high priority.'
Tusla says where a child is awaiting a dedicated social worker, they are supported until a one becomes available.
Terry Dignan, the chief executive of Empowering People In Care, said a shortage of staff is one of the main reasons for the problem.
"Tusla have been struggling, both with the recruitment of social workers and retention of social workers," he said.
"I think on both of those areas we would be looking...for a strategy that Tusla would implement around both recruitment and retention of social workers.
"The lack of social work cases being allocated to children of high priority, I think that has to be addressed as a matter of urgency."
