NHS trusts are encouraged to report incidents that put patients at risk
More than 5,700 patients in England died or suffered serious harm due to errors latest figures for a six-month period show.
The National Patient Safety Agency said there were 459,500 safety incidents from October 2008 to March 2009 - the highest rate since records began.
Patient accidents were the most common problem, followed by mistakes made during treatment and with medication.
Experts said the health service had to do more to eradicate errors.
The NPSA operates a voluntary reporting system whereby the onus is on hospitals, GPs and mental health units to record problems themselves.
It has meant that ever since the programme was launched in 2003 the number of mistakes being reported has been rising as more and more trusts join the scheme.
The last six months have been no different with the overall figure representing a 12% rise on the period before.
The NPSA now has 382 of the 392 trusts on board.
A breakdown of the latest figures show that in two thirds of cases - 303,016 - there was no harm to the patient, while a quarter - 122,246 result in low harm, which included minor injuries from things such as falls resulting from poor safety practices.
Another 28,521 - or 6% - resulted in moderate harm and 5,717 - 1% - in death or severe harm, which is classed as permanent injury or disability.
NPSA chief executive Martin Fletcher said the involvement of most trusts showed that the health service was willing to learn from its errors.
"This will help build an even stronger safety culture of reporting and learning to prevent harm to future patients."
Katherine Murphy, of the Patients Association, agreed the increasing involvement was encouraging.
But she added some of the levels of mistakes being made were too high.
"Patients shouldn't have to face a postcode lottery on patient safety."
And Peter Walsh, of Action Against Medical Accidents, said the reporting of safety incidents should be made mandatory, adding: "Not to do so would be a travesty."