A new report has shown that Ireland will have the highest percentage of people aged under 15 in Europe by 2010.
The study by NCB stockbrokers also shows we will have the lowest proportion of over 65s.
The report says that while the population of the 25 countries of the EU is expected to stay broadly the same until 2020, the population of the old EU-15 will rise as people from the newer member states move around for employment.
NCB's report says there will be marginal growth in the 15-64 age group in the EU-25 until 2010, but in Ireland the 15-64 age group will rise much more sharply than in any other European country.
Ireland will be trailed by Luxembourg, Cyprus, the UK and France.
The rate of population aged over 65 and under 15 is set to be quite stable in the EU for the next four years before rising sharply.
However, this figure will be low in the accession states because of low numbers in the over-65 age group.
The report from NCB also says that, proportionally, Ireland will receive the biggest number of its immigrants from the accession countries.
It also says that Ireland, Luxembourg, Cyprus and Portugal are expected to have the biggest immigrant flows per 1,000 population in the years ahead.