Tusla has committed more than 300 data breaches since GDPR legislation was introduced two years ago.
According to freedom information files, 43 were deemed to be 'high risk' breaches.
They include errors with postal addresses, incomplete redactions of documents and lost or stolen papers.
Tusla says it's making 'extensive improvements' to data protection governance.
But Sinn Féin's spokesperson for children, Kathleen Funchion, says the breaches are unacceptable