Health reporter, BBC News
The Tories have pledged to invest in single-sex rooms
The government has failed to live up to its manifesto promise to phase out mixed-sex wards in hospitals in England, the Conservatives say.
Responses from 132 hospital trusts to a Freedom of Information request found that 15% still used at least one open-plan, mixed-sex ward.
Others had curtains dividing the sexes, falling short of advice that there should be solid full-height partitions
The government said progress was being made but admitted there was more to do.
Labour pledged to end mixed-sex accommodation in both its 1997 and 2001 manifestos.
By 2006 ministers were claiming it had been achieved in 99% of cases, but patient surveys soon showed this to be untrue.
A government report in 2007 accepted 15% of trusts still had not achieved it.
Under the government's definition of mixed-sex accommodation, patients should be kept in bays divided at the very least by fixed full-height partitions.
Patients should also not be expected to walk past others of the opposite sex to go to washing or toilet facilities either.
Intensive care and A&E departments are not included for practical reasons.
The Tories' freedom of information request on mixed-sex accommodation - the second of its kind carried out in the past year - was answered by 132 hospital trusts and 55 mental health trusts. For the latter, there was just one (2%) that had a mixed-sex ward.
As well as the use of "Nightingale" wards, 16% of hospital and 8% of mental health centres relied on curtains.
And nearly a third were failing on the requirement that patients should not walk past those of the opposite sex when they were going to use washing or toilet facilities.
The issue of mixed-sex accommodation has become a priority for the Tories.
Last year they promised they would fund a huge rise in single rooms, guaranteeing expectant mothers and mental health patients their own rooms.
Shadow health secretary Andrew Lansley said: "Patients have enough to worry about without having to suffer the indignity of being placed in accommodation that affords them too little privacy.
"Despite hearing promise after promise to end the scandal of mixed-sex wards, we have not seen the necessary action and they continue to blight our hospitals."
Joyce Robins, of Patient Concern, said: "It is scandalous that mixed-sex wards are still being used.
"It is degrading to patients. Hospitals are just too busy."
Dr Anthony Halperin, from the Patients Association, said the government had not given the full facts, with 30% of all wards sharing toilet facilities.
"Men and women find that very embarrassing, and it nullifies having single-sex wards."
He said mixed-sex wards were about keeping beds occupied all the time, and were simply a "question of cost".
The Department of Health said surveys suggested just 2% of patients were unhappy over their privacy.
A spokesman added: "We are reducing mixed-sex accommodation to an absolute minimum and have made significant progress.
"Some hospitals and local NHS areas still have more to do and they are now required to publish and implement ambitious plans to improve."