A survey of more than 25,000 NSW emergency department patients has found they are mostly positive about their hospital experience.

More than 80 per cent of patients treated in emergency rooms at NSW public hospitals spoke positively of their care.

A survey of 26,000 patients in 2013-2014 released on Thursday found that 82 per cent had responded that their overall care was "very good" (52 per cent) or "good" (30 per cent).

Meanwhile, 65 per cent said they would speak highly of their emergency department experience, if they were asked by family and friends.

NSW Bureau of Health Information (BHI) chief executive Dr Jean-Frederic Levesque said it was a positive result considering the stressful nature of emergency departments.

The survey helps build a picture of patient care over the 76 NSW public hospitals.

"It's enabling us to assess some aspects that only patients can talk about," Dr Levesque said.

"So this is really new information that hospitals can look at to identify if there are areas where some improvements can be made."

Parking presented itself as issue. Just under half had no qualms, but 53 per cent found it to be a problem.

There were also some areas that had more favourable responses than others.

Hospitals in the north of Sydney had favourable responses compared with those in Sydney's west.

Health Minister Jillian Skinner is investigating the findings.

"I have asked for greater detail about why some hospitals are not performing as well as others and how the lessons of success can be shared," she said in a statement.