Accident and emergency services are to be removed from Whiteabbey and Mid-Ulster hospitals in a fortnight.
The Northern Health Trust said the units would be replaced by minor injuries units.
Inpatient cardiology services are also being moved from Whiteabbey to Antrim Area Hospital.
Over the next few months, the remaining acute medical beds from Whiteabbey and high dependency beds from Mid Ulster will also be transferred.
The remaining medical beds will move from Mid Ulster by mid 2011.
Emergency ambulances will be redirected to the nearest accident and emergency department once the units in Whiteabbey and Mid-Ulster close on 24 May.
The Northern Health Trust’s Colm Donaghy said the changes had been planned for some time and were approved by the health minister in September 2009 after a 16-week period of consultation.
"Members of the senior management team – including myself – will be meeting with staff groups over the next two or three days to advise them of the service changes," Mr Donaghy said.
"I want to reassure staff that the trust will work to ensure that changes will not lead to any compulsory redundancies for those who work at the two local hospital sites.
"We are currently engaging with trades unions to ensure the safe transfer of services and to support staff affected."
The health union Unison said it would be raising the moves with the health minister.
"The high-handed manner in which the trust has behaved has caused deep distress," it said.
"We now face a massive challenge to protect the services, the patients and the staff."
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