Nearly 178,000 people are waiting to be seen by a consultant at an out-patient clinic, since being referred by their GP.
Over 300 patients have been waiting more than four years to be seen at a clinic, according to new information collected for the first time by the Health Service Executive.
The new recording system shows that 167,825 patients are still waiting to be seen by a consultant after being referred by their GP since January last year.
A further 10,129 patients are still waiting to be seen at an out-patient clinic in ten hospitals, since being referred before January 2011.
The HSE has asked all hospitals to start reporting out-patient waiting lists before January 2011, but this validation exercise will take time.
Over 6,800 of the patients indentified so far have been waiting between one and two years for an out-patient appointment.
The HSE report relates to 30 hospitals and the figures are likely to rise when all remaining hospitals commence reporting.
Among the big hospitals not included are St Vincent's in Dublin, University Hospital Galway and the Mid-West Regional Hospital in Limerick.
The hospitals with the largest out-patient waiting lists since January 2011 are Tallaght Hospital in Dublin (18,785), Waterford Regional (15,117), Beaumont Hospital (13,831) and Cork University Hospital (12,387).
Under new rules, hospitals are required to date stamp each referral on the date of receipt and to enter them immediately on their systems.
The new reporting system shows that over half of referrals for an out-patient appointment are in just five specialties - general surgery, orthopaedics, ear, nose and throat, ophthalmology and general medicine.
St James's Hospital in Dublin is the only hospital reporting no patient waiting more than six months.
Some hospitals are also reporting a high level of patients who do not attend for a new out-patient appointment.
The main hospitals affected are the Royal Victoria Eye and Ear and Connolly Hospital in Dublin, St Luke's Hospital in Kilkenny and St John's Hospital in Limerick.
Meanwhile, new figures show that the HSE is over budget by nearly €90m at the end of February.
Consultants say 10% more patients treated
The Irish Hospital Consultants Association said its members have treated 10% more patients in the past two years and were working well beyond their hours to provide services.
It said that increased patient demand and resource cuts meant it was proving difficult to treat all patients as quickly as consultants would like.
The Irish Medical Organisations said the publication of the figures is an important first step, but that more specific details of waiting times were required.
The Irish Patients Association said that people who were waiting years to be seen could die as a result of the delays.
It said that with more people abandoning private health insurance the burden on the public system is likely to become even greater.
