The latest figures from the National Treatment Purchase Fund show that 560,251 people were waiting for a first public hospital outpatient consultation at the end of last month.
The NTPF figures also show that almost 69,671 patients were awaiting an appointment for inpatient or day case treatment.
There were 22,758 patients waiting to receive an appointment for a gastrointestinal endoscopy.
The Irish Hospital Consultants Association said it was extremely concerned at the continuing deterioration in the number of people on waiting lists.
IHCA President Dr Donal O'Hanlon said the record 560,251 figure was an increase of almost 49,000 patients, or 9.5%, on the same time last year.
He said the number waiting more than 12 months for an outpatient appointment had increased by 21,000 since the start of this year.
Dr O'Hanlon said that around 500 permanent consultant posts were unfilled and he called on the Government to sit down with the association to address the issues, which he said were preventing the filling of one-in-five permanent positions.