In-patient wards used by the elderly at Dover's Buckland Hospital are to close by the end of October, despite a campaign to keep them open.
12,000 people signed a petition to keep Buckland Hospital open
A report by Eastern and Coastal Kent Primary Care Trust (PCT) said the buildings, which are over 100 years old, are no longer "fit for purpose".
The future of other services is also in doubt, but the PCT said they would remain open in the short term.
Dover MP Gwyn Prosser said he would challenge the closure decision.
PCT spokeswoman Dr Amanda Harrison said it was providing better care for people in Dover, particularly the elderly.
"Care for people to stop them going into hospital in the first place and where they need a little bit of extra help when they leave hospital is best provided out of a hospital setting," she said.
She said she could not see a long-term future for Buckland Hospital because health care had moved on.
Mr Prosser said a public consultation about the future of the hospital, during which 12,000 people signed a petition to keep it open, had been a sham.
"Yes, people said they wanted improvements to their services, but they said they wanted to be looked after within the present Buckland Hospital," he said.
"I am going to ask Kent County Council health scrutiny committee to look again at these decisions."