There were 7,775 people on trolleys last month, a rise of 51% over the figures for May.
In a statement, the Irish Nurses and Midwives Organisation said: “This figure represents the highest ever level of overcrowding in the month of June since the INMO started Trolley Watch over 12 years ago.
“The figures also confirm that, for the 12th month in a row, the level of overcrowding has increased when compared to the same month in the previous year.”
INMO officials have demanded much more investment by the Government to address what they are calling a “growing crisis”.
General secretary Liam Doran said: “More capacity and more staff — it’s as simple as that. Our health service is too small. The key message is we need more beds. That requires more staff [and] more government investment.”
The figures also confirm that a number of hospitals are enduring a marked increase in the level of overcrowding.
The worst percentage increases occurred at St Vincent’s University Hospital in Dublin which had 484 patients on trolleys, up 332% on June 2014.
The increase was followed by University Hospital Waterford with 181 patients, up 178% on June 2014 while Beaumont Hospital in Dublin had 757 patients on trolleys, an increase of 150% over the same period.
More modest percentage increases occurred at University Hospital Limerick (653 patients), University Hospital Galway (670), Our Lady of Lourdes Hospital, Drogheda (728), and Connolly Hospital in Dublin’s Blanchardstown (459).
The INMO also believes the figures confirm that the actions put forward by the emergency department taskforce in April have not to date, had any impact, and much more investment by Government is required.
“The level of deterioration, and the resulting compromising of patient care and excessive workloads on nursing staff contained in these figures, is truly shocking,” said Mr Doran.
“In order to address this crisis, ahead of the winter period, the Government must allocate emergency funding which must be ongoing. This must allow for the additional bed capacity and staff required to care for admitted patients in a safe and dignified way, as the current situation is deplorable and cannot continue.”