Figures from the National Treatment Purchase Fund show that 584 patients are waiting over a year for surgical treatment.
The average waiting time for all hospital treatments has fallen to 2.3 months, which is the lowest level ever.
However, the number of people waiting over three months for hospital treatment has increased by over 1,000 to 19,377.
Of those waiting over a year for surgery, almost half are at four Dublin hospitals - Beaumont, Children's University Hospital Temple Street, Our Lady's Children's Hospital in Crumlin and Tallaght.
University College Hospital Galway has 2,400 adult patients waiting three months or more for surgery, followed by the Mater Hospital in Dublin with 1,533 patients and Beaumont Hospital with 777 patients.
In the case of children, Our Lady's Children's Hospital in Crumlin has 689 patients waiting three months or more for surgery.
Nationally, over 5,600 patients are waiting six months to a year for surgery.
The data was compiled from 44 hospitals.
The NTPF figures do not include patients who have been waiting up to three months for treatment.
