More than 9,600 patients have been treated in hospital without a bed this month, according to the Irish Nurses and Midwives Organisation.
At least 3,000 patients have been waiting on trolleys in the three most overcrowded hospitals alone, according to the union.
Figures from the INMO's Trolley Watch campaign reveal that a total of 9,635 patients went without a hospital bed this month.
The most overcrowded hospital in the Republic was University Hospital Limerick, with 1,735 patients waiting for beds during September.
That was followed by 1,263 patients at Cork University Hospital and 959 at University Hospital Galway.
INMO deputy general secretary Dr Edwards Mathews said hospital workers were now heading into the hardest period of the year without enough staff to safely care for patients.
“The number of people who will be treated on trolleys will continue to grow over the coming months,” he said.
“Our members are extremely discouraged to be heading into another winter period without safe staffing levels, and with a HSE strategy in place to prevent recruitment into vacant positions.
“Additional bed capacity must be prioritised and all obstacles to recruiting nurses and midwives need to be removed urgently. Continuing to obstruct safe staffing in this way is simply irresponsible, and will without a doubt lead to worse outcomes for patients this winter.”
