More than half of all new nurses registered in the State in 2006 came from outside the European Union, according to a new study on nurse migration carried out by the Royal College of Surgeons in Ireland (RCSI).
Most of these were from India and the Philippines.
The study also revealed that most of the migrant nurses do not intend to stay in Ireland on a long-term basis.
Dr Niamh Humphries of the Population Health Sciences Division at the RCSI, who was the lead researcher on the study, said the Irish health system had clearly become reliant on migrant nurses.
Given this - and the fact that many plan to leave Ireland again - she said the State needed to identify what the consequences of their departure would be and what could be done to encourage them to stay.
The study, funded by the Health Research Board, found that between 2000 and 2006, some 9,441 nurses were issued with work authorisation or work visas, 90 per cent to nurses from India and the Philippines.
The bulk of the remainder were issued to nurses from South Africa, Australia and Nigeria.
It also found that the numbers of non-EU nurses registering to work in Ireland rose rapidly over the same period.
In 2000 just 14 per cent of new entrants to the nursing register were from outside the EU, but by 2006 non-EU nurses accounted for 57 per cent of new entrants on the register.
"Overseas nurse recruitment does not appear to have abated as had been widely expected following the once-off demand for nurses created by the gap year in nursing graduations in 2005," the study states.
"An increased local supply of nursing graduates in recent years has not diminished Ireland's need for migrant nurses.
"Ireland, until recently a net exporter of nurses, is quickly reaching nursing migration levels comparable to those found in countries with a much longer history of skilled immigration," it adds.
The study warns, however, that while there is data on the arrival of migrant nurses to Ireland, minimal data is available to track their progress through the Irish health system.
The study concludes that consideration must be given to the long-term sustainability of Ireland's reliance upon overseas nurse recruitment, particularly in light of global competition for nurses.
Meanwhile, in-depth interviews with 21 migrant nurses between June and November 2007 found that only four intended to remain in Ireland on a long-term basis.
Three had made definite plans to emigrate to Canada, with a further eight intending to leave within the next five years, some to go home, some to migrate to the US or Australia.
Issues such as citizenship and immigration procedures were most frequently mentioned as the determining factors in the decision to leave Ireland.
"Joined-up policy thinking is needed to ensure that migration policies do not conflict with the long-term staffing requirements of the Irish healthcare system," the study said.