The Children's Rights Alliance is calling on the State to stop sending abroad for specialised care.
It's after new figures, released to Newstalk, show 21 Irish children are being looked after outside the country - with 20 in the UK and one in Spain.
The practice is costing the taxpayer up to €2.2m a year.
In a statement, Tusla said it is sometimes necessary to send a child abroad because the level of care they need is not available in Ireland.
Barnardos CEO Suzanne Connolly said the situation is far from ideal.
“The children we are particularly concerned about are the children that are placed in residential care abroad,” she said.
“The reason they are placed there is because we don’t have the facilities here to meet their particular needs.
“Some of those children will have very violent behaviour which puts them at risk both personally and can put others at risk.
“Also it means that they come into contact with the criminal justice system. So they are placed in specialist residential facilities in the UK.”
She said the children have often “lost all contact with their own network” by the time they eventually return to Ireland.
“Then, they are extremely vulnerable to homelessness and to poor mental health themselves," she said.
“So we would be very concerned about that cohort of children and we need to have the facilities to meet their needs here in Ireland.”
The Children's Rights Alliance CEO Tanya Ward said children have a right to be cared for in their own country.
“We need to be looking at an at-home solution – particularly given the situation of Brexit,” she said.
“There are very particular issues about sending a young person over to the UK for this type of care because when they do go over, they become detained at her majesty’s pleasure.
“So you are actually being treated under the UK system which does have some different rules to our own system so I do think we need to look at a more permanent solution.”