Nearly 640 people who say they were abused as a child have not been allocated a social worker by Tusla.
Fianna Fáil is condemning the new figures.
The term 'retrospective abuse' refers to abuse that an adult experienced as a child.
According to new figures from Tusla, which relate to September 2019, there are 1,541 of these cases open at present.
While just over 900 of them have been allocated a social worker, 638 have not.
Anne Rabbitte, Fianna Fáil's spokesperson for children, says it is a huge concern.
"There could be children being abused at this moment as we speak, all the while the case of an adult who has been brave enough to come forward to disclose that they were the victim and we have other victims being abused without any addressing of the matter," she said.
"I've huge concerns about it. I believe when history will be written it won't be kind to how we have dealt with priority cases and retrospective cases."
More than 5,100 children who are living in the community have not been allocated a social worker by Tusla.
634 of these are deemed high priority cases, with nearly a third - 192 - in Dublin South Central.
A further 472 children in state care have not been allocated a social worker.
