Trade union delegates have committed to working towards 50-50 female representation in elected roles of the ACTU and its affiliates.
A survey conducted in September 2014 showed 56 per cent of union members are women.
But the chair of the ACTU's women's committee Julia Fox says this overstates the proportion of women in unions, since only 21 unions were surveyed and these all had a high number of female members.
In 2015, 40 per cent of president, vice president, secretary and assistant secretary positions were held by women.
Delegates at the ACTU's triennial congress in Melbourne on Wednesday unanimously voted to aim for at least 50 per cent.
Ms Fox reported that since 2010, 45 per cent of unions had reported an increased focus and resources for women's issues.
But the number of women attending the congress is down this year, with 38 per cent of delegates female compared to 48 per cent in 2009.
The final report on last year's survey will be given to the ACTU executive in July.