Campaigners have packed the first of a series of meetings to discuss proposals to downgrade services at two out of three hospitals in West Sussex.
Campaigners say plans will create an "A&E desert" in central Sussex
Scores of people attended the consultation at Clair Hall in Haywards Heath on Thursday.
The Princess Royal, along with two other hospitals, risks losing its emergency and other acute services.
At the meeting the West Sussex Primary Care Trust (PCT) explained how the planned changes would benefit patients.
The trust wants only one hospital in the county to have the full range of A&E, emergency surgery and consultant-led maternity services.
The three hospitals that could lose their A&E provision are the St Richard's at Chichester, Worthing and Southlands, and the Princess Royal, in Haywards Heath.
Health bosses said that under the proposals the remaining A&E service would be "souped-up" and more paramedics would be on hand to treat patients at the scene of an accident.
It also outlined its plans for a series of urgent care centres that would deal with less serious injuries.
One woman, who took part in a protest outside the hospital before the meeting, said: "I led the campaign six years ago to save the A&E at this hospital [The Princess Royal] for all the reasons that we know.
"There will be an A&E at Brighton and an A&E at Redhill and they'd be a desert across the whole of central Sussex."
Shadow health secretary Andrew Lansley also visited the hospital in Haywards Heath on Thursday.
He said: "What we are fighting for is not to see services shut down and have to re-open them, we're fighting to maintain services."
The consultation period ends on 30 October, with a final meeting at Martlets Hall in Burgess Hill.