The NHS recorded 459,000 patient safety incidents in a six-month period as a result of errors and near misses, figures have shown.
The National Patient Safety Agency (NPSA) revealed that 5,700 patients died or suffered serious harm in England between October 1, 2008 and March 31, 2009.
The figures, a 12% increase on the previous six months, indicated that 5,717 (1%) of cases resulted in death or severe harm to the patient, with 28,521 (6%) resulting in moderate harm.
In other instances, 27% resulted in low or minor harm to the patient, while 66% resulted in no harm.
The most commonly reported incident was an accident involving the patient that could possibly have been prevented (32.8% of reports), followed by errors or near misses with treatments or procedures (10.1%) and medication (9.4%).
Reports were provided by 382 out of the 392 health trusts in England. Overall, there has been 3% rise in the number of trusts reporting errors or near misses.
NPSA chief executive, Martin Fletcher, said: "National reporting and learning means that the lessons learnt from safety problems are not trapped within the walls of one facility but can be spread across the NHS to prevent similar events occurring.
"More reports do not mean more risks to patients. Indeed quite the reverse."