The INMO has highlighted Letterkenny University Hospital as one of the ones which registered the highest year on year increases in overcrowding during the month of October.
So far this year, almost 4,000 people have spent time waiting for in-patient beds at the hospital.
In the latest analysis of its Trolley and Ward Watch figures, the INMO finds that Letterkenny University Hospital had a total of 121 waiting for admission over the course of October 2016, compared to 459 in October 2017, an increase of 279%.
In the year to date from January 1st to October 31st, a total of 3,972 people spent time on Emergency Department trolleys or overflow areas of wards, compared to 1,219 over the same period last year.
That's an increase of 226%.
The pressures are continuing at the hospital in November, yesterday morning there were 38 people awaiting admission, with the Full Capacity Protocol implemented and people urged to stay away from the Emergency Department.
The INMO says more acute beds are urgently needed, along with the recruitment of more nurses to staff them.