More than 100 people were given the wrong medical care in the past year.
The national summary of adverse events for the 2019/2020 year shows there were 115 events which must always be reported regardless of whether there was harm to the patient.
It showed treatment was given to the wrong consumer 44 times and performed on the wrong site 56 times.
An item was left inside a person's body 11 times, one person was given the wrong implant or device and three people were given the wrong blood.
None of those botch-ups resulted in death or permanent severe loss of function but in 20 cases the patient had permanent major or temporary severe consequences.
The report, published by the Health Quality and Safety Commission, pointed out all those events could lead to serious harm or death but were preventable.
The number of events was on par with the previous year where 114 of those events were reported.
Health Quality and Safety Commission board chair Dr Dale Bramley said every adverse event had a consumer and their family at its centre.
"It is our duty to continually strive to improve how we manage and learn from these events, and how we communicate with and support all those who have been affected," he said.
"I would like to acknowledge all those who were harmed by the events reported here and the significant impact this has had on you and your whānau."
In total, 975 events which resulted in harm to the patient were reported during the year and 627 of them were reported by district health boards.
There were 112 pressure injuries, 73 adverse events caused by delayed diagnosis or treatment and 55 serious harm events caused by deterioration of the patient prior to treatment being given.
There were 231 falls in the year and 87 femur or hip fractures.
The number of events reported by mental health and addiction services dropped from 232 in 2018/19 to 218 this year although there were still 180 suspected suicides reported.
"The reduction in the adverse event community suicides is welcome but it is too early to say whether this is a trend," the report said.