Plans to demolish the QEll Hospital in Hertfordshire to replace it with a smaller unit and build 202 homes on the site were discussed on Wednesday night.
Welwyn Hatfield Borough Council hosted a public meeting to reveal details.
Clinical services and the number of patients expected at the new unit in Welwyn Garden City were discussed.
Protesters said people would face a long journey to the Lister Hospital in Stevenage for maternity, A&E and other services they expected to have locally.
NHS Hertfordshire is leading the development of the new hospital in partnership with local GPs.
Managers said it would include a local A&E facility available 24 hours a day, every day of the year, but protesters claimed this was just an emergency care unit.
Other services at the hospital will include a general outpatients, GP services, diagnostics - such as MRI, X-rays and ultrasound, a unit to support elderly people, day treatment unit, ante and post-natal services, children's centre and breast clinic.
'Glorified health centre'
The overall site may also include some beds for older people who need extra support to help them when they leave a major hospital.
The outline planning application for the new QEII site has been submitted to Welwyn Hatfield Borough Council, with a decision expected later this summer.
Barry Cross, speaking for the 20-strong protest group at the meeting, said: "The new hospital will have no accident and emergency, no maternity department and no mental health facilities.
"What they are proposing is an emergency care service and there has not been enough public consultation.
"People now face a long journey to the Lister Hospital in Stevenage and they will not be able to cope.
"I hope there is not major accident like the Hatfield rail crash because the plans show it is nothing more than a glorified health centre on a quarter of the original hospital site.