Too many NHS staff still do not report lapses in patient safety, MPs say.
Nearly 1m patient safety lapses occurred last year
The Public Accounts Committee said nearly a quarter of incidents and 39% of "near misses" go unreported, with doctors being the worst culprits.
And the cross-party group said more should be done to cut the number of errors, especially those which cause serious harm or death.
Nearly 1m lapses in patient safety were recorded in 2004-5. The government said lessons were being learned.
The committee, which based most of its findings on a report by the National Audit Office last year, also attacked the National Patient Safety Agency for failing to provide enough advice on improving safety.
The NHS agency was set up five years ago to develop a national reporting scheme to help the NHS learn lessons from lapses in safety.
One in 10 patients are estimated to be unintentionally harmed under the care of the health service. These can include medication errors, equipment defects and patient accidents, such as falls.
But the committee said the system was too complex and the agency was not offering value for money.
The MPs also said there had been a lack of progress by NHS trusts in the last six years since a report by the chief medical officer attacked the "blame culture" that existed in the NHS for hampering the improvement process.
The study said few NHS trusts "have formally evaluated their safety culture" and "insufficient progress" had been made on achieving targets set out by the Department of Health.
And it added only 24% of trusts routinely inform patients involved in a reported incident and 6% do not involve patients at all.
Many trusts are also not complying with safety alerts issued by the NPSA.
Committee chairman Edward Leigh, a Tory MP, said: "What this points to are two related and deep-seated failures.
"One is the failure of the NHS to secure accurate information on serious incidents and deaths.
"The other is the failure on a staggering scale to learn from previous experience."
Peter Walsh, chief executive of the charity Action Against Medical Accidents, said: "We hope the report will give an injection of urgency into work to improve patient safety."
But Chief Medical Officer Sir Liam Donaldson defended the NHS, saying improvements were being made.
He added: "Over the last five or six years we have put in place a comprehensive patient safety framework in this country which is admired internationally."
NPSA joint chief executive Susan Williams said: "The NPSA has already acted on a number of issues identified in the report and will work with the Department of Health to consider the report's recommendations carefully.
"The agency remains committed to helping improve patient safety in the NHS and working with the local NHS to deliver this."