An investigation by RTÉ has found that hospital consultants in 14 out of the country's 47 acute public hospitals treated more private patients than they were allowed to under a contract agreed with the HSE.
Under the 2008 Hospital Consultants' Contract, consultants are employed full-time by the HSE for salaries between €113,000 and €229,000 to work between 37 and 39 hours per week in the public system.
In return, under the 2008 contract, 66% of all hospital consultants agreed to limit the amount of private work they do.
Up to 80% of their patients are supposed to be in the public system with the remaining 20% being private patients.
However, RTE investigates found that between 2015 and 2016 consultants in 14 out of the 47 acute public hospitals exceed the 20% limit, meaning fewer public patients are being treated.
Their figures, obtained under Freedom of Information, show that overall consultants are meeting the 80/20 ratio.
But their numbers show this is only because some hospitals adhere to the ratio exceptionally well by treating very few private patients and this offsets the numbers from other hospitals who are very lax when it comes to restricting the proportion of private patients treated by consultants.
The investigation goes on to reveal that a sizeable number of regional hospitals are significantly off target with the resultant negative impact on public patients.
The investigation found that more than 19,500 private patients were treated than was allowed in 2015, with that figure rising to nearly 24,000 in 2016, meaning around 43,000 public patients on waiting lists in this two year period missed out on treatment to private patients.
Up to 2,700 consultants work in Ireland's 47 acute public hospitals.
RTÉ Investigates - Public v Private: the Battle for Care will be broadcast tonight on Prime Time on RTÉ One at 9.35pm.