New figures show 36 children, who were in care in the Dublin South West/ Kildare/West Wicklow region at the end of December, were without an allocated social worker.
A total of 440 children were in care in the region at that date.
Nationally there were 6,258 children in care at the end of 2016, 453 of which who were without an allocated social worker.
The figures came to light during parliamentary questions in the Dáil this week.
The Minister for Children and Youth Affairs, Katherine Zappone said addressing the number of children who are without an allocated social worker is a key priority.
Tusla is now in the second year of a three year plan to ensure that a social worker is allocated to all children and young people who need one.