The purpose of the National Health Index (NHI), including the National Health Index number (NHI number), is to help with the planning, coordination and provision of health and disability support services across New Zealand.

The purpose of the National Enrolment Service (NES) is to provide a real time view of a person’s health providers. 

The purpose of the Medical Warnings System (MWS) is to warn health providers of any known risk factors that may be important when making clinical decisions about individual patient care.

Unique identification

The NHI number is the unique identifier for all patients who receive healthcare in NZ and is the cornerstone of clinical and administrative patient-related information. Very rarely do health providers rely on names alone for identifying patients. The NHI number identifies the patient for referrals, visits to the hospital, tests, medication prescriptions and patient-related correspondence. Correct identification of the patient is a critical aspect of clinical safety.

Linking information

The NHI number ties together all patient information and patient systems. The NHI number is on patient labels, which are used on most items of patient documentation, from pharmaceutical labels to discharge summaries.

Where regional services exist, such as centralised diagnostic services, health providers may receive the diagnostic results electronically from an external source.

The NHI number is used to ensure that the results are associated with the correct patient.


The NHI number is used:

  • for communication with patients, for example, when advising patients about an outpatient appointment or an inpatient booking
  • to report patient events to national data collections, such as those held by the National Testing Centre, the Centre for Adverse Reactions Monitoring and the Ministry of Health
  • for communications with other health professionals relating to patients, for example when a patient is:
    • referred to a hospital
    • referred or transferred to another specialist within the hospital
    • referred or transferred to another hospital
    • discharged from the hospital
    • discharged to another healthcare facility, such as a rest home.

Accessing information

The NHI number is used to:

  • obtain information from the hospital’s internal systems, by allowing online access to information such as diagnostic results, previous clinical events, or planned future events such as elective surgical bookings
  • access information from the MWS, such as medical warnings, medical alerts, and previous secondary care events
  • access information from the National Immunisation Register, such as immunisation status
  • access information from the National Enrolment Service.

Coordination and contact

The NHI number is used by:

  • the hospital’s community health service, to coordinate and manage its visits (for example, for community health nursing or mental health contacts)
  • screening programmes, to coordinate and manage the programme; this includes tracking and contacting clients and potential clients, and managing clinical information
  • public health units, to coordinate and manage patient-based public health services such as immunisation and school dental services
  • General Practices, pharmacies and other community providers to coordinate and manage visits and to record clinical and administrative information about health interactions.

Data collections

The NHI number is used to uniquely identify health information in national and regional clinical databases that are accessible to approved health providers.

  • Medical Warnings System (MWS). The MWS is designed to warn health providers of any known risk factors that may be important when making clinical decisions about individual patient care. This data can be accessed only through the NHI.
  • National Immunisation Register (NIR). The NIR is designed to assist vaccinators to increase New Zealand’s immunisation coverage through timely access to immunisation histories.
  • Regional Clinical Data Repositories (CDR).  CDRs make patient information available to all providers that are providing care to a patient.
  • National Enrolment Service (NES). NES records a patients choice of regular provider of health service e.g. GP

The Ministry of Health uses a coded form of the NHI number to uniquely identify health and disability support events on statistical databases. The databases are used to:

  • produce statistical publications
  • meet international reporting requirements
  • assist with developing policy
  • facilitate research
  • support the planning of health and disability support services, including health needs assessment
  • assist with monitoring the performance of health and disability support services.

An encrypted form of the NHI number is used in statistical databases to help protect the privacy of individuals while enabling data from different places to be linked.