Hundreds of Oxford University students could fail to graduate after amassing debts of £200,000.
Some students at the university's Pembroke College have fallen behind in rent as the recession starts to bite.
They have been warned that degree certificates will be withheld if students fail to clear their debts.
Students have traditionally charged their rent, food and course fees to their 'battels' - a form of tab - which is paid off at the end of term.
But the collective overdraft at Pembroke - where Samuel Johnson, JRR Tolkien and J William Fulbright studied - has now reached £200,000.
The university is now pledging to "chase students" falling behind on their repayments.
John Church, the bursar, said: "In the greater scheme of things the money owed is not a great deal but we want to reduce the amount so the finance committee has decided to chase students up for the outstanding debt.
"If debts are not paid students will not formally graduate and some have actually decided not to take their final exams - they obviously don't have mothers to make proud.
"Students who refuse to pay will be punished. At the end of the day they owe the college the money and it must be paid."
It is not the first time the system has led to unrest.
More than a decade ago students went on a rent strike following an increase in bills. More recently, students at St Hugh's College have threatened similar action.
The tradition of battels - which goes back centuries at Oxford - has been criticised for encouraging students to get into debt.
A spokesman for the Citizens Advice Bureau said: "Using this system of credit should be banned. We have had a number of students come to us in great distress because they have got themselves into debt.
"Some students who don't have much financial help from their parents are dangerously close to bankruptcy.
"The college might furnish these young people with an academic education but they are neglecting to teach them how to manage their finances. In today's climate that is essential." (By Graeme Paton, Education Editor Last Updated: 3:48PM GMT 10 Feb 2009)