There are 592 patients waiting for beds in Irish hospitals today.
The figures were released as part of the INMO's Trolley Watch.
417 patients are waiting in the emergency department, while 175 are in wards elsewhere in the hospital.
University Hospital Limerick is the worst hit hospital today.
The total number waiting on trolleys is up on Tuesday's figure, when 578 admitted patients were waiting for beds.
The worst hit hospitals today are:
Yesterday, Cork University Hospital set a record for the number of admitted patients on trolleys with 74 waiting.
There were 62 admitted patients waiting in the hospital's emergency department and a further 12 on wards.
The INMO's industrial relations officer in Cork, Liam Conway, said patients in CUH were being treated in corridors, waiting areas and other inappropriate places.
“All of those patients are being put at risk, and our members are once again being asked to simply fill in the gaps left by short staffing and inadequate planning,” said Mr Conway.