The figures from the INMO show CUH was the second most overcrowded hospital with 898 people without a bed- compared to 350 for the same month last year.
University Hospital Limerick remains the most overcrowded in the country with 1,823 people waiting for a bed during May.
The nursing union says May has been an extremely difficult month for staff and are calling for the HSE to urgently reconvene their Emergency Taskforce to discuss solutions.
