The Medical Council's Fitness to Practise Committee has found five allegations of poor professional performance against Dr Colm Quigley to have been proven.
Dr Quigley is Clinical Director at Wexford General Hospital.
He is a former president of the Medical Council and also a former president of the Irish Hospital Consultants Association.
The inquiry related to Dr Quigley's treatment of an unnamed patient, Patient X, who was referred to Dr Quigley's private clinic at Ely Hospital in Ferrybank in Wexford in August 2009.
The patient had low sodium levels.
After the consultation, Dr Quigley wrote to Patient's X's GP and said he would be carrying out a series of tests on the patient.
The tests were never carried out.
The patient died of lung cancer on 16 April, 2011.
Chairman of the committee Danny O'Hare said today that it had not been alleged that any error on behalf of Dr Quigley had led to a deterioration in the patient's health or death.
The committee found that Dr Quigley had failed to ensure he had an adequate system in place for tracking or monitoring tests.
Four other allegations against him were not proven to have amounted to poor professional performance.
Last month, Dr Quigley told the inquiry that he accepted the patient "did not have his tests done in a timely fashion".
However, Dr Quigley told the inquiry that he believed subsequent examination of medical records had shown that the patient in 2010 had not contracted the cancer that killed him. Therefore the missing tests could not have revealed it in 2009.
The recommendations of the committee will be forwarded to the board of the Medical Council, which will decide what, if any, sanctions will be taken.
