One of Scotland's most exclusive universities accepted just five students from the most deprived areas, a study has found.
The University of St Andrews took one student from the least well-off 10% of society for every 28 students it accepted from the the top 10%, according the National Union of Students (NUS).
St Andrews counts Prince William and his wife Kate, the Earl and Countess of Strathearn, among its alumni.
NUS Scotland has called on MSPs to force universities to widen access to students from deprived areas.
Young people from affluent backgrounds are more than twice as likely to attend university than deprived youths.
For every student from the most deprived backgrounds recruited to university across Scotland, there are 2.5 students from the least deprived background.
There has been a small increase in the proportion of students from the 20% most deprived backgrounds in the past five years from 10.6% to 11.6%.
The NUS estimates that it would take 40 years for Scotland's universities to reflect society at the current rate of improvement.
The NUS report, entitled Unlocking Scotland's Potential, calls on the Scottish Parliament to introduce enforceable widening access agreements with Scottish universities, and for universities to scale up their widening access work, including differential offers, routes for applicants to "top-up" school grades and larger-scale summer schools.
Robin Parker, NUS Scotland president, said: "Universities can't do it all when it comes to fair access, but they can clearly do a great deal more.
"The Scottish Government have done a lot in this area in recent years by abolishing fees, protecting places and pledging to increase student support.
"Scottish universities now must do their bit. Our report shows that our universities are clearly missing out on people with huge potential from our most deprived communities."
He added: "We hope over the next few years Scotland can yet again lead the way, and show that universities can recruit more talented people from poorer backgrounds, can improve standards through doing so, and ensure that university is open to those with the talent to do well at university not just those from particular backgrounds."
Aberdeen University has a ratio of one deprived student for every 22.5 rich students it accepts, while Edinburgh University has a ratio of 1:12.
The top two constituencies in Scotland for progression to higher education are Eastwood and Edinburgh Southern, with 68% and 52.2% of all school leavers going on to higher education, and the bottom two are Banffshire and Buchan Coast and Glasgow Provan with 26% and 24.9% of all school-leavers going to higher education.