A patient being given the wrong blood product, mistakes in the clinical process and four falls resulting in serious harm were among errors at Rotorua and Taupo hospitals in the year to June.
The Lakes District Health Board has reported nine serious adverse events in the 12-month period, one of which involved the death of a patient.
Almost half of the events, four of the nine, involved patient falls which resulted in serious harm such as fractured hips.
Others included errors or issues with assessment, diagnosis, treatment and general care of a patient.
The health board's quality and risk manager Lesley Yule said staff were mindful of the patients and families involved in those events and the board "regretted any harm caused to patients during their care".