The results of the first year of a screening programme based at the Mater Hospital Emergency Department have revealed high rates of undiagnosed HIV infection in Dublin.
Almost three in every 1,000 people who took part in the programme were diagnosed with the infection.
The test is carried out by using an oral swab HIV kit and takes around 30 minutes.
Doctors say the rates are high by international standards.
Dr Ger O'Connor, emergency medicine physician at the Mater, said 6,000 people participated in the first year.
He said 4,900 people were tested and 14 people returned positive results.
Under the programme, routine attenders to the hospital's Emergency Department are offered a confidential, rapid HIV test combined with a video-based counselling and information service.
The results demonstrate a prevalence of HIV of 2.85 cases in every 1,000 taking the test, higher than the one in 1,000 prevalence for which widespread screening is recommended.
Dr O'Connor said people should know their HIV status, as early diagnosis helps people with HIV to get the full benefits from treatment and can also prevent unintended onward transmission.
The programme also shows that an emergency department can be an ideal setting for HIV screening, if implemented in the right way.
The M-BRiHT Study will continue testing until the end of 2014 and is a joint initiative involving the Mater Hospital Emergency Department and the Jacobi Medical Centre in New York and is coordinated through University College Dublin.