Administrators at the Royal Cornwall Hospital at Treliske are blaming the government for a possible £5m overspend this financial year.
The chief executive, Brian Milstead, reckons the funding formula is wrong and he believes Treliske is underfunded by up to £15m a year.
The Health Minister admits rurality may be a key factor in funding, but says there will be no changes before 2008.
Mr Milstead is reassuring patients that care will not suffer.