The stigma and embarrassment surrounding mental health is stopping sufferers seeking vital help, experts have warned.
The new study showed 45% of people would not willingly accept someone with a mental health problem as a close friend, with 65% admitting they would discriminate against hiring someone with a history of mental illness as they may be unreliable.
The survey, carried out for St Patrick's University Hospital, also revealed a quarter of those quizzed believed people with mental health problems were of below average intelligence.
Paul Gilligan, St Patrick's chief executive, said stigma remained a major hurdle for people accessing mental health services.
"It is a sad fact that because of this stigma, many sufferers feel embarrassment and shame and are reluctant to seek appropriate supports," said Mr Gilligan.
The survey - launched to coincide with mental health awareness week - was carried out on 240 members of the public nationwide and focus groups in Leinster.
Almost four out of 10 felt undergoing treatment was a sign of personal failure.
However, it also revealed exposure to mental health problems was widespread, with 55% of respondents having a close member of their family - such as a parent, child, brother, sister - treated for a condition.
Another 61% stated close friends had had help and more than half confirmed they worked with someone who had emotional or mental health problems.
Professor Jim Lucey, medical director at St Patrick's, said society needed to understand and accept mental illness.