Figures from the Irish Midwives and Nurses Organisation (INMO) show there was 10,515 treated on trolleys or chairs in October.
The hospital with the highest amount of patients without a bed was University Hospital Limerick, with 1,876 patients without a bed.
Cork University Hospital had 1,126 patients treated on trolleys, while University Hospital Galway had 989 patients without a bed.
INMO General Secretary Phil Ní Sheaghdha said:“The fact that over ten thousand sick people were treated on a trolley this October is a grim indicator for the level of overcrowding we are bound to see over the winter period.
“Staffing is an issue across all hospitals. Not having a safe number of nursing staff in our emergency departments, inpatient wards, long term care and community services continues to exacerbate the persistent problem of overcrowding in our hospitals.
“Again this winter, our members are not assured that their safety and that of their patients is a priority. The HSE and Government must protect frontline services by lifting the recruitment embargo immediately and accelerating the hiring process, which has been hindered by the current pay and numbers strategy.
"These delays now result in nearly 12 months to approve replacements for essential nursing and midwifery posts. Without the safe level of staffing patients cannot be assured of a safe service, this is avoidable and must be corrected immediately.”
On Friday, there are 441 patients on trolleys. 338 people are in emergency rooms across the country, while there is 103 patients elsewhere in hospitals.
University Hospital Limerick has the highest number of patients without a bed, with 92 people on trolleys. Of those patients, 42 people are in the emergency department.
Cork University Hospital has 51 people without a bed, with 46 people in the emergency department.
