Female graduates earn thousands of pounds less than their male counterparts, according to a report.
The pay gap persists even between men and women from the same types of university who studied the same subjects, suggests the study.
Researchers for the Higher Education Careers Services Unit (Hecsu) analysed how much students who applied to higher education in 2006, earned last year.
Jane Artess, of Hecsu, said pay distribution was "strikingly uneven".
This was despite laws designed to ensure equal access to jobs and pay, said Ms Artess,
The researchers analysed data from a longitudinal study of 17,000 recent graduates called Futuretrack. They found that the take-home pay of more than half of female graduates ranged between £15,000 and £23,999.
Men were more likely to take home £24,000 and above, they found.
The analysis did not include part-time workers or the unemployed.
The data, published in the Hecsu journal Graduate Market Trends, suggested men earned more than women across all degree subject areas, even if more women took those subjects than men.
"When graduate earnings are examined by subject, it is clear that women earned less than men who studied the same subject," says the article.
The authors add this is the case across all subject areas, "even where women's participation is greater than men's".
"Equal opportunity to access jobs and pay has been enshrined in legislation for 40 years, yet Futuretrack found that being female can make a difference to a graduate's earning power", said Ms Artess.
"It is difficult to see why this is, for example, female graduates of media-related subjects are no more or less numerous than their male counterparts yet their earnings are typically lower.
"Of the Futuretrack respondents, there were fewer men than women in law, yet there is an even greater male lead on earnings.
"Since it would be unlawful for employers to pay males and females doing the same job differently, something else must be happening to female graduate earnings.
"If we look at wages by sector, the male lead is persistent in the public and private sectors, in graduate workplaces and also in graduate and non-graduate job roles.
"The only area where female pay is equal to males is in the not-for-profit sector," said Ms Artess.
Trades Union Congress (TUC) general secretary Frances O'Grady described the findings as "very alarming."
"We know that women pay a huge motherhood penalty, but this data suggests earnings disparities may be starting earlier.
"More women are going to university and are better educated than ever before but are not getting the same reward when they leave as male graduates.
"This research shows they are getting a raw deal for their talent."
Heather Jackson, a businesswoman and author who advocates a better gender balance among senior managers, said the results were disappointing but unsurprising.
Managers should take note that "a raft of research published over the last decade has shown that gender diversity and the right balance of talent can be a contributing factor to business performance, so there is a strong business case to ensure that we nurture female talent from the very start of their careers", said Ms Jackson.
A government spokeswoman said that although the gender gap was closing, "it is still too large".
"We have already made good progress towards ending pay discrimination," she said.
"Measures in the Equality Act to make pay secrecy clauses unlawful have already been implemented.
"We are also encouraging companies to sign up to Think, Act, Report, a voluntary initiative to improve gender equality at work, including reporting on pay and other work-place issues.
"More than 70 companies have signed up, covering 1.3 million employees.
"But for all this, pay inequality remains a stubborn obstacle to real fairness in the work-place.
"We will continue to work with businesses to ensure that we do all we can to help them make the most of women's talents, and unlock their full potential."
The Futuretrack project is carried out for Hecsu by Warwick University's Institute for Employment Research.