The Health Information and Quality Authority has found that 177 cases of retrospective referrals of child abuse were awaiting allocation to social workers last August in Tusla's Dublin southeast and Wicklow area.
The social services watchdog says the waiting list posed a significant risk and that there is not enough staff in the area's child protection and welfare services.
The report relates to an announced inspection of the fourth largest service area in the State's Child and Family Agency.
Inspectors reviewed 258 case files and met five children.
Over the previous two years, 52 referrals of institutional abuse and one case of organised abuse were received by the service.
The report states the 177 cases of retrospective referrals was high and that due to the fact that a potential risk to children had not yet been determined, it posed a significant risk.
Staff told inspectors that addressing these cases was complex and they had not received any training for the task.
In terms of organisational and Institutional abuse, the report states the area manager maintained a list of such referrals.
She told inspectors she had contact with safeguarding officers from the diocese and religious orders and that systems to manage the individuals concerned had become increasingly robust in recent years.
HIQA says there was good practice in the management of organised abuse and the service worked closely with An Garda Síochána in relation to this.