Female directorship across the ASX 200 stood at 27.7% between March and May, with the ASX 100, ASX 50 and ASX 20 achieving a 30% or higher rate of women on boards, according to the Australian Institute of Company Directors.

The rate of companies meeting the 30% target rose by 10 to 84.

Fortescue Metals Group led the ASX 200 with 55.6% female directors, followed by OZ Minerals with 40%.

Mining services firms Orica and WorleyParsons each had 37.5% female directors.

The other miners with more than 30% directors were Alumina, Lynas Corporation, South32 and BHP.

Alumina joined the ranks of having more than 30% female directors when John Pizzey retired in March, while Iluka Resources left the list with the appointment of Robert Cole.

There are still 60 boards with only one female director, including 14 miners, and five with no female directors, down from 13 this time last year.

Having joined the ASX 200 in March, Ausdrill is now the only miner without a female director.

However, it has a female chief financial officer (and current acting CEO) in Theresa Mlikota.

Pilbara Minerals had previously been the only miner without a female director until the appointment of Sally-Anne Layman in April.

The overall rate of female board appointments dropped to 48.5%, with year-to-date appointments standing at 49%, comprising 47 women versus 49 men.

"The AICD set our 30% target in 2015 because of the strong body of evidence showing that diverse boards lead to better outcomes for shareholders and stakeholders alike," AICD chairman Elizabeth Proust AO said.

"The obstacle to achieving this target has long been one of demand, not of supply. Australia is not lacking for talented and experienced women, and the breadth and depth of experience of female appointees in 2018 is evidence of that.

"However, even with the current year-to-date female appointment rate of 49%, achieving the 30% target by the end of this year will be tough."