Women hold only 9.3 percent of directorships in the entire private sector, the Ministry of Women's Affairs says.
Most of the NZX's top 100 companies don't have any and women account for just 21 percent of management positions reporting directly to chief executives.
The ministry says NZX's new diversity listing rule will help change that.
It was announced yesterday and companies with a balance date on or after December 31 have to comply.
Their annual reports must provide a gender breakdown of their directors and officers.
The ministry's acting chief executive, Kim Ngarimu, says it follows the launch of the 25 Percent Group last month.
The group includes the chairs, directors and chief executives of 12 leading organisations and is committed to achieving 25 percent female participation on private sector boards by 2015.
"Initiatives such as these will lead to more opportunities for women on boards and to improve corporate performance," Ms Ngarimu said today.
NZN