Figures from the Health Service Executive show that almost 6,000 people over 75 have experienced a wait time of more than 24 hours in a hospital emergency department so far this year.
It comes as the Irish Nurses and Midwives' Organisation reveal their latest trolley watch figures, which show record levels of overcrowding.
The HSE set a target for 2017, that those aged over 75 would be discharged or admitted to an emergency department within 24 hours of registration.
But figures show that so far this year, 5,880 people over the age of 75 were waiting longer.
The information was requested from the HSE by Fianna Fáil's Health spokesperson Billy Kelleher.
He described the 24-hour target as "pathetic" and "setting the bar way too low".
Speaking on Morning Ireland, Mr Kelleher said that he understands that all hospitals are under pressure but that the issue needs to be urgently addressed.
"The targets set are not being met... and it has got worse in the intervening years. Even their target, which lacks ambition and probably compassion and they can't even meet that target," he said.
"Targets set are not being met... and it has got worse" - Fianna Fáil's Billy Kelleher on 6,000 elderly people waiting over 24 hours in A&E pic.twitter.com/1oAyWA47VA— RTÉ News (@rtenews) August 10, 2017
A 2012 Health Information and Quality Authority report recommended that the total patient time spent in an emergency department should be less than six hours.
Mr Kelleher also voiced his concern over the number of people on trolleys in emergency departments during what is supposed to be a quiet period.
In a statement, the HSE said that total attendances at emergency departments this year are up 2% on last year. Admissions are also up 3%.
It said there has also been an increase in attendances by people aged 75 years and older.
The HSE said it recognises the importance of a system-wide focus, on improving patient experience times, in particular in respect of older persons.
It said that longer wait times for older people can be as a result of intervention in the emergency department by a 'Frail Elderly Assessment Team', whose primary aim is to assess, treat and discharge the patient, in preference to assessing and admitting the patient.
Latest trolley figures from the Irish Nurses and Midwives Organisation (INMO) show record levels of overcrowding compared to previous years, with 57,674 people on trolleys waiting admission to a hospital bed in the first seven months of 2017.
However, the number of people on trolleys in July 2017 is down 6% on the July 2016 figure.
"If we have a high spike already in August, as we progress into winter we could have a very, very serious crisis in terms of patients and the numbers on trolleys," Mr Kelleher said.
His comments came as the INMO said that there are 351 patients waiting on trolleys or on wards today for admission to a bed.
Speaking on RTÉ's News at One, INMO President Liam Doran said that increasing capacity is the only way to address the crisis in Emergency Departments.
He said an increase in the care people can receive at home will help ease overcrowding in hospital emergency departments.
He said: "Capacity, capacity, capacity. The only way to look after the ageing population we have, the rural divide, and so on is by significantly developing our community nursing services our home help services and home care so I can be looked after at home.
"But that doesn't mean a half an hour in the morning and the evening and nothing on a Saturday and Sunday, the multi-mobility issues will come back and hit me and I'll end up back in the ED, so you need more capacity in the community to keep me out."
Damien McCallion, the HSE National Director with responsibility for Planning Emergency Care has said no-one finds today's trolley figures acceptable.
Speaking on RTÉ’s Drivetime, he said the HSE needs to try and improve how it manages older people in the health system.
He also said additional investment is needed in primary care.
Mr McCallion said: "In terms of the current resources, we are trying to look at how patients flow through the system from the community into the hospital; we are trying to use whatever additional funding we have to try and increase capacity, not just in terms of acute beds, but also in terms of home care and social care.
So, I suppose, within the resources we have, we are trying to work with those hospitals which are under the greatest pressure."
The hospital worst affected is Galway University Hospital with 36 patients waiting.
Other hospitals badly affected are Wexford General, which has 31 patients waiting, and Waterford University Hospital, where 29 patients are waiting for a bed.
Some hospitals have no overcrowding such as Beaumont and Connolly Hospitals in Dublin,which each just have one patient waiting according to the INMO.