Women teachers are paid pound;250 less on average than their male colleagues from day one of their careers.
The gap widens to pound;1,850 when the salaries of all full-time qualified teachers are taken into account, according to Department for Education and Skills figures for 2001.
Women have tended to fall behind men in pay and promotion because they take career breaks to have children. But a pay gap for new entrants to the profession, revealed in the latest School Workforce in England statistics, suggests other factors at work.
Vestiges of discrimination and headtachers' use of recruitment and retention points to attract teachers of shortage subjects could be causes, say classroom and headteacher unions. A high proportion of men in the profession teach in the shortage subject areas.
In primary schools, new female entrants aged up to 39 generally earned the same or up to pound;110 more than men of the same age.
But at secondary, only the under-25s started on the same average salary of pound;16,410. A 45-year-old woman starting teaching could expect to earn an average pound;17,640, pound;930 less than a male starter of the same age.
Julie Mellor, chair of the Equal Opportunities Commission, said: "Schools need to examine the criteria they use to set pay when they recruit and promote staff to make sure they are not biased against women. There is no room for complacency about equal pay in the teaching profession."
However, she said, female graduates in other jobs can be earning 15 per cent less than men by age 24.
Male science and maths teachers, who receive additional recruitment and retention points could be skewing the figures, said one union spokeswoman.
While John Dunford, general secretary of the Secondary Heads' Association, suggested men may be better at bargaining for their initial salary.
Men continue to dominate the top jobs in primary and secondary schools.
Almost a third of secondary heads are female, compared to a quarter in 1997: men make up 46 per cent of all secondary teachers. In primary, women make up 61 per cent of school leaders but 84 per cent of the workforce.
Statistics of Education: School Workforce in England, 2002, www.dfes.gov.ukstatistics