Doctors, surgeons and hospital chefs are among the worst at hand hygiene.
Figures from the latest Health Quality and Safety Commission National Hand Hygiene report, conducted over four months, reveals medical practitioners across all district health boards had a poor rate of hand washing - 57.1 per cent. The national standard is 70 per cent.
Of the 3,416 washing opportunities for medical practitioners, only 1,952 were acted upon, the report found. The 1,464 incidents when handwashing didn't take place are considered chances for infection to spread to patients.
Student doctors' compliance was 41.7 per cent and domestic staff, including cleaners and those working with food, was 35.6 per cent.
The poor handwashing record comes a week after an Environmental Science and Research study found superbug infections had risen nearly 10 per cent.
The well-known "hospital bug" - methicillin-resistant staphylococcus aureus or MRSA - is often spread via dirty hands.
ESR senior scientist Helen Heffernan, who examined data from 2005 to 2011, found significant increases of MRSA in most district health boards.
However, she said the superbug had become more prevalent in communities than hospitals during the past decade.
Waitemata District Health Board associate director of nursing Jenny Parr said healthcare workers should wash their hands at five key moments: before and after seeing patients, before and after procedures and after leaving a patient's surroundings.
The report found the lack of handwashing for all healthcare workers occurred most after leaving patients and before procedures.
"[Doctors] wash their hands before and after seeing the patient but we are talking about five moments, which is adding a level of complexity that people might not have known," Parr said.
The district health board's infection control team implemented a programme a year ago that increased compliance from 49 to 73.1 per cent.
Parr said it was achieved through robust audits, providing the right equipment and posting up signs about the possible consequences.
In May last year, associate health minister Jo Goodhew called for better tracking of how often healthcare workers washed their hands. "Clean hands save lives, it's as simple as that," she said."
Top 5 winter woes
• Whooping cough
• Rheumatic fever
• Hand, foot and mouth