Hemel Hempstead Hospital is to be stripped of its acute services despite a 30-year campaign to keep services in the town.
West Hertfordshire Hospitals trust made the decision last week.Work to move services will start in the new year and should be completed within 18 months.
Acute services - including accident and emergency - will be based at Watford General Hospital and elective surgery will be at St Albans City Hospital.
Plans to return elective surgery to Hemel once an independent treatment centre is built are now in the balance as local primary care trusts are re-examining the need for the centre.
It is not yet known whether the move will lead to job losses.
Acute trust chief executive David Law said some services would remain at the Hemel site, including outpatients and diagnostics.
Hertfordshire PCTs are also expected to set up an urgent care centre at Hemel, and the
A&E department will not move until both this and an acute admissions unit at Watford are established.
Trust chair Professor Thomas Hanahoe said: 'We acknowledge the feelings of anxiety within local communities; however, I believe
the changes that we have now approved are fundamental to ensuring a strong, vibrant and high-quality health service in West Hertfordshire.'