Bed-blocking by over-60s cost Great Western Hospital in Swindon £80,000 last year, it has been revealed.
A BBC Wiltshire investigation has found that one patient had been at the hospital unnecessarily for more than two months.
A hospital spokesman said delayed discharges had come down by 47% in the past two years, but the figures have risen again in the past few months.
He said it cost the hospital £200 a day to accommodate patients.
The research came as part of the BBC's week-long Living Longer campaign, which is looking at the effect an increasing ageing population could have on different regions.
The figures were 762 in 2008/09, and went down to 402 in 2009/10.
But Alf Troughton, medical director at the hospital, told the BBC that the figure had doubled in the past three to four months.
"We were going along nicely at probably less than 10 a week and now we're up to about 30," he said.
He said the patients often did not have anywhere else to go.
"I think social services have found it very difficult to get plans for these patients to find places to put them," he added.
Figures for Salisbury District Hospital showed delayed discharges over the past three years were down by 76%.
Professor David Oliver, national clinical director for older people, said organising nursing homes and residential homes for elderly people with medical problems could take some time.
He said: "It's good to hear that Swindon's actually halved the number over the past couple of years and the government's committed to improving the situation further.
"In the Spending Review there was a further £1bn announced to go to social care through the National Health Service and a further £1bn straight to local government.
"There's very much a focus on trying to join up health and social care so we get the right person in the right place at the right time for their needs."