The government has announced a shake-up of systems to improve patient safety as a study finds current safeguards are failing.
Nearly one million lapses in patient safety were recorded in 2004-5
NHS staff should ensure incidents involving serious patient harm are reported within 36 hours, says the chief medical officer's (CMO) report.
It calls for a blame-free culture where staff feel confident to report, plus quicker and simpler reporting systems.
A British Medical Journal study says most are missed by the current system.
The National Patient Safety Agency (NPSA) estimates that 900,000 incidents a year result in harm or near harm to NHS patients.
Earlier this year MPs said nearly a quarter of incidents and 39% of "near misses" go unreported, with doctors being the worst culprits.
They criticised the National Patient Safety Agency for failing to provide enough advice on improving safety.
The CMO report recommends the NPSA refocus its efforts to concentrate on collecting and analysing patient safety information.
Plans are also afoot for a national campaign to encourage clinical staff to report incidents.
These can include medication errors, equipment defects and patient accidents, such as falls.
Most incidents 'missed'
The York University authors of the BMJ study analysed data from the local reporting system in a large NHS hospital trust in England as well as case notes for the same patients.
A national forum of key patient safety agencies to facilitate learning, share best practice and co-ordinate delivery
Ensure incidents involving serious patient harm are reported within 36 hours as well as "near misses"
Establishment of patient safety action teams at local level to provide support to frontline staff
More involvement of patients and their families in promoting patient safety
From a random sample of 1,006 admissions, 324 patient safety incidents were found - 136 (42%) resulting in patient harm.
The 21 incidents missed by case note review were minor, whereas the 130 incidents missed by the reporting system led to patient harm.
Thus, the routine reporting system missed most patient safety incidents that were identified by case note review and detected only 5% of those incidents that resulted in patient harm.
Chief Medical Officer Sir Liam Donaldson said: "Improvements have been made across the NHS to embed patient safety into everyday practice.
"However, more needs to be done to accelerate the pace of change in this area."
He added: "Often it is systems that have failed, rather than any individual being at fault."
A spokesman for the NPSA said: "We endorse the move to an open and fair culture where staff feel confident to report, as the more we know about the sort of incidents that occur, the more we can do to address problems.
"We're already seeing a change in reporting patterns."