910 adults who were abused as children were referred to Tusla in the first four months of this year.
In April, the agency was dealing with a total of 1,481 'retrospective abuse' cases.
564 had not been allocated a social worker, including 149 in Waterford and Wexford.
Tusla says the waiting lists have fallen over the past year.
But Galway East TD Anne Rabbitte, the Minister of State at the Department of Children, says the delays are still unacceptable.