The Health and Disability Commissioner received 1400 complaints this year - many about treatment at public hospitals.
In a report that covers his first year in the role, Anthony Hill says complaints included concerns about delays in service, diagnosis, the adequacy and appropriateness of treatment, complications, co-ordination of care and referrals to other services.
Mr Hill says the office closed 1355 complaints, which was 169 fewer than for the previous year.
He puts the difference down to extra complaints last year over a contentious change in laboratory testing contracts in Auckland.
Radio New Zealand's health correspondent says 27 investigations were begun, compared with 51 the former year. They led to 11 findings that patient rights had been breached.
Almost a quarter of disability-related complaints concerned rest homes.