The proportion of female directors on the boards of FTSE 100 companies has risen, according to latest data from the Professional Boards Forum (PBF).
Women made up 19% of FTSE 100 directors on 1 October, up from 17.4% in May this year and 12.5% from three years ago.
The government wants 25% of FTSE 100 directors to be female by 2015.
Business Secretary Vince Cable said the latest figures showed good progress was being made to achieving this.
Since March, 25% of FTSE 100 board appointments have been women.
There are six all-male boards left in the UK's index of top companies (Antofagasta, Croda, Glencore Xstrata, London Stock Exchange, Melrose, Vedanta) down from 21 in February 2011.
The 25% target by 2015 was set by Lord Davies, former trade minister, in a report commissioned by the government in 2011.
Mr Cable has written to firms with all-male boards asking them what steps they were taking to address the issue.
He said: "Businesses are clearly still striving to get the right mix of talent around their boardroom table and we must not lose that momentum.
"We have until 2015 to reach our target of 25% of women on the boards of listed companies which Lord Davies set us two years ago. With today's encouraging figures, I am confident we can get over the finish line.
"But appointing more women as non-executive directors is not an end in itself. This is about more talented women getting executive experience, so that they will not only advise, but run this country's great companies."
Sixty-six more women directors need to be appointed to reach in the 25% target, according to the PBF's BoardWatch report.
Among FTSE 250 companies, 14.9% are female, up from 7.8% in February 2011. Some 20.4% of boards are all-male, down from 52.4%.
There had been calls to set board quotas to ensure that female presence is given a boost. But Katja Hall, chief policy director at the CBI employers' group, said: "These figures show the voluntary business-led approach is working and we are pleased to see we are on the way to reaching our 25% target.
"Businesses can only secure the best leaders if they look at the widest pool of candidates and greater diversity in the boardroom also improves decision making.
"If we are to remove further blockages in the pipeline of female talent to the top, business leaders must continue to improve recruitment, mentoring and succession planning."