A leading union has called for urgent action in the Midlands to tackle the "chronic" job segregation and undervaluing of women's work.
The demand followed new research for the GMB which showed that fulltime women in Birmingham worked about 93 per cent of the hours worked by men, for 76.8 per cent of the pay.
When the difference in hours was taken into account, the city gender pay gap was 16.2 per cent.
The margins were even more stark in other areas across the region, rising to as high 25.1 per cent in Coventry and 23.1 per cent in Solihull.
The findings came as part of a national survey revealing examples of workplaces with high levels of job segregation and under-valuing of women's work, including a food factory where most shopfloor workers were women and most managers were men; and a supermarket where most checkout staff were women and the majority of managers and drivers were men.
Debbie Coulter, GMB deputy general secretary, said: "We would urge West Midlands employers to work with unions to identify the reasons for the gender segregation within their workplace, to agree strategies for eradicating gender pay imbalances and for providing equality of opportunity for half of Britain's workforce."
She explained that the analysis of the pay gap had been adjusted for the differences in hours worked by full-time men and women.
The study had used used figures from the 2004 Annual Survey of Earning and Hours from National Statistics.
It proved conclusively that job segregation and the lack of equal pay for work of equal value " accounted for the lion's share of the pay gap."
She said: " Action is needed from employers throughout the education and skills provision system.
"This exists throughout British industry and is accepted as the norm in most of the private sector.
"It is possible to address the pay gap imaginatively and progressively as is the case in areas of the public sector. Among professional groups there is greater equity between men and women as traditional barriers are being dismantled."