A report into child and adolescent mental health services (CAMHS) has found 197 young people were admitted to adult wards between 2007 and 2009.
The report, carried out by the health watchdog, the Regulation and Quality Improvement Authority, (RQIA) welcomed a purpose-built CAMHS facility.
It acknowledged "progress had been made" in mental health services since the publication of the Bamford Report, but there was more to be done.
Overall 21 recommendations were made.
The Bamford report was published in 2006 and found that CAMHS in Northern Ireland was "under-resourced, fragmented and lacking in strategic approach".
The report found things have improved since 2006. It said the purpose built inpatient facility in Belfast has aided the range and availability of CAMHS, particularly in areas such as eating disorders and crisis intervention.
However, the report said it was still concerned over the number of young people admitted to adult mental health wards between 2007 and 2009.
Glenn Houston, RQIA chief executive said the findings raised concerns about child safety.
"If a child goes into an adult ward that raises immediately issues about safeguarding that child in those circumstances," he said.
"Clearly it is much easier to do in a hospital that has single rooms. But not every adult psychiatric ward would be able to offer every young person a single room."
The report made a total of 21 recommendations for the Department of Health, the HSC Board and the five Health and Social Care trusts.
It criticised the absence of an overall CAMHS strategy, access to help and early intervention services.
Mr Houston said that a key recommendation was that, through policy guidance, the department for health should set up a model for CAMHS provision across Northern Ireland.
"We believe that the implementation of these recommendations can drive further improvements for all those accessing child and adolescent mental health services in NI."
Mr Houston said the review team found the key issue was to ensure children and young people with mental health needs were seen by the right person at the right time.
"Whilst we welcome the new inpatient facility in Belfast the report highlights the need to ensure young people from across NI can access the service.
Mr Houston also paid tribute to the commitment of staff working the area.
"The specialist mental health services provide essential support to young people and their families and carers," he said.