Women in full-time work in Scotland earn 12% less than male colleagues, a study marking the 40th anniversary of the Equal Pay Act has found.
The disparity is highest in senior management roles and in the financial sector.
Women's salaries were found to be up to 55% less than those of men in similar full-time positions.
The Equality and Human Rights Commission (EHRC) report said the pay gap "remains a stubborn reality".
The EHRC said full-time female workers earned, on average, £113 a week less than men.
The gap widened considerably when comparing the earnings of part-time workers, with women receiving on average 32% less than men.
Discrimination, stereotyping and the fact that women bear the brunt of childcare, were found to be some of the reasons for the pay gap.
The gap fell by just 2% last year, compared with the previous year.
Kaliani Lyle, EHRC Scotland Commissioner, called on companies to speed up the pace of change and address the problem by adopting transparent pay policies and flexible working practices.
She said: "Although it's encouraging that the pay gap between men and women is closing, it is nevertheless very slow progress - 40 years since the Equal Pay Act and women are still paid on average 12% less than men in full-time employment in Scotland.
"Clearly significant changes need to take place, and that means changing habits and practices."
'Transparent pay policies'
Ms Lyle wants employers to measure and report on their gender pay gap.
She said: "By understanding that they have a problem, companies can start to take steps to address it.
"We also know that adopting flexible approaches to work can make a big difference in helping to close the gap."
Ms Lyle warned that the EHRC would use enforcement powers to "address any persistent and significant problems".
She said: "We are encouraged by the firms which are developing transparent pay policies and flexible approaches to work, but there aren't enough of them.
"The many need to learn from the few."
Emma Ritch, project manager for Close the Gap, which works to address the gender pay gap, said: "After 40 years, the fact that such a large and widespread gap still exists is not only an issue of equality and social justice, but is bad for business and bad for Scotland's economy."