There were over 1,000 cases of children going missing from State care between 2018 and 2020.
They range from people aged 11 to 17.
The new figures, released to Newstalk under the Freedom of Information Act, include boys and girls in special care, along with voluntary, private and Tusla care.
There were 319 cases of children going missing last year, with 366 in 2019 and 330 in 2018.
Almost half involved children going missing from private residential care centres.
Barnardos CEO Suzanne Connolly said the figures are concerning.
“Children who are placed in residential care have high levels of need and they often come from chaotic home environments in which there are very few household rules or boundaries,” she said.
“Therefor they can find it really hard to settle into the structure of residential care life. They then abscond and can engage in quite risky behaviour which puts both themselves and others at risk.”
She said children can be at serious risk when they abscond.
“They absolutely could be a danger to themselves because what you sometimes find is children and young people are going to reengage with what we would call a negative peer network,” she said.
“They might be getting involved in either joy-riding or risky drug-taking behaviour or some children may be putting themselves sexually at risk.
“So, it is really important they are found really, really quickly and returned to a safe environment.”
Tusla said the majority of the cases involve children who are missing less than 24 hours.
The agency said Gardaí must be notified by care staff when a child is missing from their placement for longer than expected and the carers can't find them.