The unit is closing due to staffing shortages.
A specialist inpatient unit for children with complex, and often life-threatening, mental illnesses will be operating at half capacity for at least the next five months because of a staffing crisis.
The Psychiatric Nurses Association (PNA), which has its headquarters in Sallins, has condemned the closure of 11 of the 23 beds at the Linn Dara Child and Adolescent Mental Health Unit at Cherry Orchard hospital in Dublin.
It said the HSE has confirmed to it that the beds will remain closed until September at least because of nursing shortages.
The unit plays a vital role in providing mental health services in the greater Dublin Area.
The HSE says the reason for the closure is staff shortages with 24 staff available and 51 needed.
Psychiatric Nurses Association, General Secretary Peter Hughes said there are only 3 other CAMHS units around the country: