Thousands of protesters have marched to demand that "crazy, ill-thought-out" plans to scrap a hospital's A&E department and downgrade its maternity ward be rejected.
Under proposals being considered by the Government, Lewisham Hospital in south-east London would see its emergency department replaced with an "urgent care" ward and its maternity services turned into a midwife-led unit.
Health Secretary Jeremy Hunt is due to make his decision on the plans by February 1.
The closures are part of a radical overhaul proposed by a special administrator in response to nearby South London Healthcare NHS Trust (SLHT) going into administration after it started losing around £1.3 million a week.
But SLHT - which runs three hospitals in the capital and was the first NHS trust to collapse - does not have responsibility for Lewisham Hospital.
Campaigners say a "successful and well-run" hospital is in danger of being sacrificed due to the neighbouring trust's failure.
Dr Louise Irvine, a local GP and chairman of the Save Lewisham Hospital campaign, said: "This decision is crazy and ill thought out. It is a big mistake and carries huge clinical risks of things going wrong for patients but also political risk.
"If Jeremy Hunt can close a good local hospital here, he can do it anywhere in the country - nowhere is safe.
"This is very much a national issue, there are 60 hospital trusts across the country under threat of bankruptcy, many of them very good hospitals.
"We are saying 'look at Lewisham, if we can win then you can win'."