For further information about this collection or to request specific datasets or reports email

The National Minimum Dataset (NMDS) is used by Health New Zealand | Te Whatu Ora, the Ministry of Health, Health District, Primary Health Organisations, clinicians, researchers and members of the public for statistical information, clinical benchmarking, performance monitoring and health service planning and research.


The NMDS is used for policy formation, performance monitoring, research and review. It provides statistical information, reports, and analyses about the trends in the delivery of hospital inpatient and day-patient health services both nationally and on a provider basis. 


The NMDS is a national collection of public and private hospital discharge information, including clinical information, for same day and multi day inpatients. Unit record data is collected and stored. All records must have a valid NHI number.

Data has been submitted electronically in an agreed format by public hospitals since 1993.

The private hospital discharge information for publicly funded events (eg, birth events and geriatric care) has been collected since 1997. Other data is being added as it becomes available electronically.

Start date

The current NMDS was introduced in 1999. The original NMDS was implemented in 1993 and back-loaded with public hospital discharge information from 1988.

Guide for use

The NMDS has undergone many changes over the years. Some data subsets have been removed and are now held in separate collections (ie, New Zealand Cancer Registry and the Mortality Collection). In other cases, additional fields have been included and events are reported in more detail than in the past. For further details refer to the National Minimum Dataset (Hospital Events) (NMDS) Data Dictionary.

Private hospital information is also stored in the NMDS. Publicly funded events (primarily maternity and geriatric) and surgical events from some hospitals are up to date. Privately funded events may be delayed.

Collection methods – guide for providers

Data is provided by public and the larger private hospitals in an agreed electronic file format. A cut-down electronic file format is reported by other private hospitals.

Frequency of updates

Publicly funded hospital events are required to be loaded into the NMDS within 21 days after the month of discharge. Electronic input files are received and processed almost every day by National Collections.

Health New Zealand | Te Whatu Ora National Collections has a team of staff who process private hospital electronic discharge reports.

Security of data

The NMDS is accessed by authorised National Collections staff for maintenance, data quality, audit and analytical purposes.

Authorised staff have access to the NMDS for analytical purposes, via Qlik and other tools. 

Privacy issues

Health New Zealand | Te Whatu Ora is required to ensure that the release of information recognises any legislation related to the privacy of health information, in particular the Official Information Act 1982, the Privacy Act 2020 and the Health Information Privacy Code 2020.

Information available to the general public is of a statistical and non-identifiable nature. Researchers requiring identifiable data will usually need approval from an approved Ethics Committee.

National reports and publications

The National Collections team publishes an annual report about hospital discharges and procedures carried out in public and private hospitals via a web tool.

The web tool provides information and statistics on publicly funded and privately funded hospitalisation data.

The web tool is updated annually.

The publication allows you to examine summarised data through interactive visualisations and understand hospital discharges and procedures in relation to demographics in Aotearoa New Zealand.

Also provided in the web tool are detailed diagnoses and procedure tables for the latest year of data available. 

View the Hospital events web tool

Past annual publications are available on the Hospital events page

Data provision

Customised datasets or summary reports are available on request, either electronically or on paper. Staff from the Data Services team can help to define the specifications for a request and are familiar with the strengths and weaknesses of the data. New fields have been added to the collection since 1988, but wherever possible consistent time series data will be provided.

There may be charges associated with data extracts.

The Data Services team also offer a peer review service to ensure that data is reported appropriately when published by other organisations.