A degree in an arts subject reduces average earnings to below those of someone who leaves school with just A-levels, a study shows.
Graduates in these subjects - including history and English - could expect to make between 2% and 10% less than those who quit education at 18, researchers at Warwick University found.
The findings come despite data showing the average university leaver earns £220,000 more than non-graduates during their working life.
Professor Ian Walker, leading the study, said: "Feeling warm about literature doesn't pay the rent.
"Maybe an average arts student knows he or she is not going to do very well. Maybe they do not.
"Education is a risk individuals take. We need to make sure people have the correct perceptions."
Law graduates did best, on average earning between 24% and 30% more than A-level school leavers.
Medicine, mathematics and engineering helped boost earnings capacity by almost as much.
But languages and education were among the least lucrative degree subjects.
The government announced earlier this year that the maximum annual tuition fee for higher education would rise to £3,000 from 2006. The current figure is £1,100.
The National Union of Students has estimated some graduates could be left with debts, including living costs, of £30,000 before staring work.
Professor Walker feels this may persuade students away from less lucrative degrees.
He said: "These are variances that might make people change their subject mix in future.
"An average degree is still a very good investment. But, although on average the rates of return on this investment are high, the
variance is enormous - some do extremely well, some don't do well at all.
"So this makes that type of investment particularly risky and may, of course, give
grounds for some kind of subsidy."
Professor Walker's findings are based on the government's Labour Force Survey figures from 1993 to 2001.
They are published in the latest issue of Labour Market Trends.