A survey by the Medical Council has found that only 50% of doctors completely agree that they should report all instances where a colleague is significantly impaired or is incompetent to practise medicine.
Almost one in seven doctors said they had direct personal knowledge of a doctor who was impaired or incompetent.
Of those who had encountered such doctors, only 41% reported it to a colleague, 36% spoke to the doctor concerned and 18% stopped referring patients to the doctor.
Just 63% of doctors believed that doctors should disclose all significant medical errors.
That compares with 77% of people who say they are confident a doctor would tell them if a mistake had been made.
The Medical Council survey involved 1,000 members of the public and 700 doctors.
The survey also found doctors are highly trusted, with over 90% of patients saying they were well cared for.
However, the survey revealed areas where the public and doctors differ, including being honest about an error in care and raising concerns about patient safety.
The main reasons given by doctors for not reporting an incompetent colleague were: No action would be taken (44%), fear of retribution (25%), or a belief that someone else was dealing with the problem (19%).
The Medical Council said that a small but important minority of the public do not trust doctors and report dissatisfaction and experiences of medical practice that have given them cause for concern.
The public awareness of Medical Council procedures to inquire into a doctor is low - just 48% are aware of fitness to practise inquiries and only 19% of people know they are held in public.
Over 18,000 doctors are registered to practise in Ireland with the Medical Council.
Speaking at the launch in Dublin Castle today, Minister of State for Primary Care Alex White said: "Leadership which puts patient safety first is essential in a changing health system."
Mr White also said the work of the Medical Council "will ensure the appropriate accountability and transparency" to maintain confidence in the medical profession.