Some 83% of children adopted in Ireland between 1991 and 2010 were from five countries: Russia, Romania, Vietnam, China and Ethiopia.
Since legislation changed in 2010 there was only one change to this list with Romania being replaced by the US.
Since 1991 some 4,989 children have been adopted by parents habitually resident in Ireland, according to the Adoption Authority of Ireland.
In the first in a series of research reports, the AAI said the vast majority of adoptions (4,282) took place between January 1991 and October 2010.
Eighty-three per cent of these children came from Russia, Romania, Vietnam China and Ethiopia.
In the nine years since the new legislation, there has been a decline in numbers, with 707 children adopted since 2010.
Of these children, 80% came from Russia, Vietnam, Ethiopia, USA and China.
The 2010 act consolidated existing adoption laws into one single piece of legislation seeking to ensure better regulation of adoption in Ireland and in respect of intercountry adoption.
The Adoption Authority of Ireland also replaced the Adoption Board under the act.