SIPTU has accused the Government and the Health Service Executive of targeting the elderly with Budget cutbacks and hospital closures.
The union's John Hubbard said the decision to close a long-stay hospital for the elderly in Portlaoise and shut more than 20 beds at St Vincent's Hospital in Athy was unacceptable.
Mr Hubbard said the decision showed that the authorities were picking on the most vulnerable people in society.
The HSE has said there will only be eight bed closures in the Athy facility, with capacity falling from 128 to 120.
The executive has also denied there is a coordinated campaign to close public hospitals for the elderly around the country.
The Irish Nurses and Midwives Organisation said it is seeking a meeting with the HSE to discuss the situation in Athy.
INMO Industrial Relations Officer Derek Reilly said: "It is apparent to our organisation that the primary reason for this closure is one of funding.
"There is sufficient staff within the hospital to keep the beds open.
"This is another devastating blow to our elderly population and a further erosion of our health services."
Elsewhere, a Labour Senator has told Minister for Health Dr James Reilly that the party's ministers in the Cabinet will not put up with the closure of any more public nursing homes.
Senator John Whelan said the closure of army barracks paled into insignificance alongside the downgrading and closure of hospitals for the elderly and there would be a national outcry if any more were closed and the Minister did not intervene.