Women are even less likely to be appointed to the board of an AIM-listed company than a FTSE 100 firm, according to the business advisory firm Deloitte.
The government's Women's Enterprise Task Force encourages women to set up businesses
Women make up only 3% of board members in companies listed on AIM, which is the stock exchange with no minimum size requirements for growing companies.
Companies listed on the FTSE 100 - the country's biggest listed companies - have 10% women on their boards.
The figure is 5% for FTSE SmallCap companies and 6% for the FTSE 250.
A recent report from the Equal Opportunities Commission predicted that it would take 60 years to have the same number of female directors as male at FTSE 100 firms - a rise from last year's projection of 40 years.
Earlier this month, the government set up the Women's Enterprise Task Force to encourage women to set up businesses.