New figures show there were over 812,000 patients on national public hospital waiting lists at the end of December.
The Department of Health says waiting list numbers reduced last year by around 4% or by over 29,800 people.
It was significantly lower than the waiting list reduction target for the year.
Last year, the Government allocated €350m under the Waiting List Plan to reduce active waiting lists for acute scheduled care by more than 132,000 patients or 18%.
Of those on the current lists, over 584,600 patients are waiting to be seen at an outpatient clinic for the first time by a consultant, according to the data from the National Treatment Purchase Fund.
There were also over 81,560 'active' patients, those waiting for an appointment for inpatient, or day case treatment last month.
Patients who have been given dates for inpatient or day case treatment are categorised separately.
There were also 58,000 patients 'suspended' from waiting lists in December for various reasons, including not being well enough to have their treatment.
The overall waiting list figures compare with 831,765 patients on national waiting lists at the end of 2021.
Dr Matt Sadlier, Consultant Group Chairperson of the Irish Medical Organisation said the waiting list has serious implications for patients because a delayed appointment is delayed care, which is delayed diagnostics and that can lead to adverse outcomes.
The Irish Patients Association said it was concerned that the recent special measures being taken by the HSE to deal with overcrowding will lead to large scale cancellation of planned operations, to free up beds but also add to waiting lists.
Stephen McMahon said patients on lists were getting letters of 'validation' from hospitals asking if they still need an appointment.
He said that the letters were being issued to patients who do not yet have a date for their surgery or outpatient clinic.
Mr McMahon said the process was complex and if patients fail to respond, the letters say thay may be removed from waiting list.
He said that patients may not be in a position to clinically say they no longer need care.
The Department of Health said that long waiters have been significantly reduced throughout last year.
It said that the number of patients exceeding the 12-month maximum wait time target for in-patient or day case treatment has decreased by around 3,800 or 22.6%.
The Department said that the inpatient and day case waiting list has increased by 6,105 patients or 8% and this can be attributed to the significant increase in outpatient activity since September, resulting in conversions to the inpatient and day case waiting list.
