The NHS needs to listen harder and learn from complaints, according to a report from health service ombudsman Ann Abraham.
The ombudsman analysed 15,579 complaints made about the NHS in England in 2009/10.
The highest proportion of complaints related to hospital, specialist and teaching trusts (44%), and those related to GPs took second place (17%).
Around 63% of the complaints investigated and reported on were upheld or partly upheld.
Of the complaints about GPs, 56% were upheld or partly upheld, and 80% of the complaints about dentists were upheld or partly upheld.
Health Minister Simon Burns said the report highlighted that the NHS needs to take patient complaints more seriously and manage them more efficiently at a local level, rather than simply relying on the health service ombudsman.
The ombudsman's office takes up patient complaints if they not resolved by NHS trusts.
