Up to 500 people are waiting on trolleys at hospitals across the country today.
The INMO says University Hospital Limerick is the most overcrowded with 66 people waiting.
St Luke's Hospital, Kilkenny is next with 42 people in need of a bed.
The organisation is calling on the HSE to continue curtailment of services to deal with the high numbers.
Health Minister Simon Harris says measures announced last week are having some benefit.
He said: "There was a huge effort to reduce some of the delayed discharges, to help get people home, to increase homecare packages, to increase the availability of transitional care beds that has assisted somewhat."