Women earn an average of 27% less than their male colleagues, new research shows.
The average man's annual salary is £30,948, compared to just £23,977 for women. Salary comparison website PayFinder.com says there is evidence the gender pay gap is widening.
The difference between men's and women's salaries is most marked in London where men get paid an average of 35% more than women - £39,022 compared with £28,833.
The gender pay divide is smallest in Northern Ireland where, at £25,998, men earn only 15% more than women.
One reason why women get paid less is that they are more afraid to ask for a pay rise. Two-thirds of women claimed they were too scared to ask for more money, compared with just a quarter of men.