A report by the Irish Patients Association shows large reductions in the number of patients being treated at the Mater Hospital in Dublin.
Increasing financial pressure is being blamed for the year-to-year performance of the Mater, which is the worst of the five teaching hospitals.
Earlier this year the hospital had to close beds, let front line staff go and also close part of a medical assessment service.
By contrast, St. James's Hospital achieved its health strategy target of having no adult patient waiting for more than one year.