Details of the 2002 Irish census have revealed that non-Irish nationals make up 5.8% of the population.
The 2002 census was the first to ask the question of nationality; previously, only place of birth was asked.
The Principal Demographic Results, released today, also show that the population of Leinster has exceeded 2 million persons – this is over half the total Irish population of 3.9 million.
These figures give a breakdown of the population by age, sex, martial status, household composition, usual residence, nationality and place of birth as well as information on the Irish language, religion and Irish Travellers.
Migration has had an effect on the religious demographic, with a decline in the percentage of Roman Catholics and an increase in the Muslim population.
The percentage of Roman Catholic adherents declined from 91.6% in 1991 to 88.4% (3.46 million) in 2002, while the number of Muslims increased almost five-fold to 19,000.
The number of people speaking the Irish language has declined in all Gaeltacht areas, except in Meath. Over a quarter of the Irish speaking Gaeltacht population speak Irish less frequently than weekly while 7.4 per cent were recorded as never speaking the language.
Lone parents have increased by a quarter in the last three years and the average number of children per family is 1.2.
Despite being the youngest population in the EU, Ireland is ageing. The State's population has aged by a year since 1996, leading to an average age of 35.1.
According to a new question introduced in the 2002 census, there were nearly 24,000 Travellers enumerated in April 2002.
To read more on the 2002 census, download the .pdf file from the CSO website.
