Campaigners fighting to get accident and emergency services reinstated at Crawley Hospital are staging a protest.
The A&E unit at Crawley Hospital closed to patients in 2004
The protesters are calling for a review of front-line hospital services around the southern section of the M25.
A spokesman said hospitals in Redhill, Kingston and Chertsey "picked up the fall-out" after Crawley lost its A&E.
Managers at the West Sussex hospital had said the move would lead to improved care when the department became a walk-in minor injuries unit.
Before the protest on Friday, a spokesman said the result of the A&E closure had been "healthcare chaos across the southern section of the M25".
'Improved care move'
He claimed hospitals in Surrey and Sussex, and the outer London boroughs, had been "regularly jammed full of patients and unable to cope with demand".
After the casualty department moved to East Surrey Hospital, Redhill, in 2004, Surrey and Sussex Healthcare NHS Trust said there would be an overall improvement in patient care at Crawley Hospital.
It also said that 75% of patients who would previously have been treated at Crawley would still be seen at the new minor injuries unit.
This year, campaigners took a 30,000-name petition to Westminster calling for the reinstatement of the A&E.