Acute paediatric services at Tallaght Hospital in Dublin are being temporarily relocated to Crumlin and Temple Street hospitals because of the Covid-19 pandemic.
Paediatric outpatient and urgent care centre services are being transferred to Connolly Hospital, Blanchardstown.
The move means the closure of services for children at Tallaght, such as inpatient, day case, outpatient and the emergency department, from midnight tomorrow.
In a statement, Children's Health Ireland, which operates the three children’s hospitals in Dublin, said the decision had been taken to protect patients, their families and staff.
In doing this, CHI said, it was supporting Tallaght University Hospital with additional staff, emergency facilities and bed capacity for sick adults.
It said its decision "is in line with other acute paediatric healthcare providers globally who have made similar decisions to support their acute adult hospital systems".
CHI has reassured patients and families that the children’s hospitals in Crumlin and Temple Street are open, including their 24-hour emergency departments.
The paediatric urgent care centre at Connolly Hospital, Blanchardstown for minor injuries or minor illnesses is open between 10am and 5pm Monday-Friday.
Dr Ciara Martin, consultant and Paediatric Executive Lead at CHI in Tallaght, said: "We are experiencing a national public health crisis, one we have never seen before.
"It is so important that all of us within the health service take whatever steps are possible to ensure that we direct resources where they are most in need to support patients and our colleagues.
"We are all committed to providing the best possible clinical care to those who need it and we believe that by taking the steps today the health system as a whole will be strengthened.
"The measures announced today for CHI at Tallaght are temporary but necessary. I want to thank the our staff for their dedication, responsiveness and flexibility during these unprecedented times."