The latest statistics for March reveal an 8.6% increase in the number of people attending their local ED, compared to the same time last year.
In that same month, 68% of patients were treated, discharged or admitted within four hours of their arrival.
That was despite the ministerial target set at 95%.
The targets also state that no patient should wait more than 12 hours to be seen, treated, admitted and discharged after arriving at any ED, but statistics show 666 patients waited half a day or more last month.
This figure represents a decline in performance in comparison to the same period last year, when 613 patients waited more than 12 hours during March 2015.
The busiest EDs in Northern Ireland last month were the Ulster Hospital in Dundonald, on the outskirts of east Belfast, and the Royal Victoria Hospital (RVH) in the west of the city.
A total of 7,971 patients attended the Ulster's ED while 7,850 patients sought emergency treatment in the RVH.
Northern Ireland's hospital Emergency Departments (EDs) remain as busy as ever, according to waiting times figures.