The number of students choosing to take university courses abroad has more than doubled in recent years, international figures suggest.
The international higher education market is very lucrative
The OECD found 2.7 million people were participating in higher education in a foreign country in 2004 - up from 1.3 million in 1995.
Between them, France, Germany, the US and UK accounted for more than half of the growing market.
This was despite the US and UK charging among the highest fees.
English language premium
UK universities demand up to $18,000 (£9,600) a year for courses for overseas students and the US up to about $13,000 (£6,900).
The OECD - Organisation for Economic Co-operation and Development - found a premium was placed on studying in the English language.
Some 25.1% of those students from OECD's 30 member countries who chose to study abroad went to the US.
The UK attracted 16.1%, while Germany took 14.2% and France 6.2%.
Overseas students are estimated to be worth several billion pounds a year to the UK economy alone.
The OECD figures do not take into account the large increase in recent years of students from countries outside the organisation, with China and India in particular seen as growing markets.
In every country looked at, graduates out-earned those people without degrees.
In Hungary this group enjoyed an average salary more than double that of the rest of the population, while in the Czech Republic a degree meant 82% more pay.
In the US and UK, the extra expected earnings were 72% and 58%.
But in New Zealand, which has among the world's highest take-up of higher education places, the difference was 29%.
On average, the OECD countries spent 5.9% of gross domestic product on education in 2003 - the latest year for which figures are available.
Iceland, on 8%, spent the most, followed by the US and South Korea, both on 7.5%.
The lowest proportion of GDP spent on education was Turkey's 3.7%, with Greece on 4.2% and Ireland on 4.4%.
Primary school class sizes also varied widely, from an average of 33.6 pupils in South Korea to 16.4 in Portugal.
Overall, the OECD average was 21.4 pupils.
Figures from more than 30 countries were studied.