UK medical students owe on average more than £20,000 by their final year, the British Medical Association (BMA) says.
It is the first time medical student debt has topped £20,000
A survey of 1,900 students suggests that by the fifth year of medical school they had an average debt of £20,172 - up nearly 5% on last year.
The BMA said the debt could partly be explained by the length of medical students' courses, and the fact they had fewer chances to work part-time.
It wants the NHS bursaries which some students can claim extended to all.
More than 100 students said they owed more than £30,000, and one in 10 had debts in excess of £25,000. One said he had debts of £55,000.
Nearly all of the students (92%) had a student loan, and almost 60% had an overdraft.
One in five had a bank loan, the average size of which was £8,580 - up 12% on last year.
The BMA said medical students following six-year courses owed an average of £22,635 at the end of their studies, an increase of 17%.
This compares with the basic annual salary for a first year junior doctor of £20,295, it said.
The additional expenses for books faced by medical students, plus the cost of travelling to hospitals and buying equipment such as stethoscopes could also be contributing factors to the high debt levels, it added.
Kirsty Lloyd, chair of the BMA's medical students committee, said the case for greater financial help for medical students was very clear.
"Making the grade as a doctor should be about talent, compassion and commitment, not on how much money you're prepared to borrow," she said.
"On top of studying hard for five or six years, medical students are expected to take on these massive debts, and from next year those who have a first degree are also going to have to pay upfront top-up fees.
Sabrina Talukdar, chair of the BMA's Scottish medical students committee, said there was no doubt that financial debt created a barrier for people from less affluent backgrounds from becoming a doctor.
"Widening access is essential so that people, from all backgrounds are encouraged to study medicine to provide the diverse medical workforce that Scotland needs.
"However, with ever increasing debts, this aim will prove difficult."
The BMA is campaigning for the NHS bursaries currently available to some students at the end of their courses to be extended to those in all years.
Higher Education Minister Bill Rammell said there was a good financial package in place to support medical students and research showed those who qualified "significantly increase their earning potential".
The average GP net income is estimated at over £83,000 in 2005, he said.
¿We have put in place a comprehensive student finance package for 2006-07, which is fairer for students.
"For example, those students starting in 2006 and who come from low income households there is a new, non-repayable maintenance grant of up to £2,700 and typical bursaries of £1,000.
¿And medical students who study for a second undergraduate degree can apply for the full-rate maintenance loan for the first four years of their course - potentially £6,170 a year.
¿From the fifth year of their course, medical students can apply for a means-tested NHS bursary and a reduced-rate maintenance loan which could add up to as much as £3,030 a year as well as having their fees paid by the NHS.¿