HL7 v2
HL7 v2 is a pipe-and-caret-delimited messaging standard first published by HL7 International in 1989. It remains the dominant messaging format in hospital integration engines worldwide, carrying ADT, ORM, ORU, SIU, MDM, DFT and other clinical and administrative events.
When it applies
HL7 v2 applies wherever integration engines are routing events between hospital systems — patient administration to clinical systems (ADT), order-entry to fulfilment (ORM), lab results to EHRs (ORU), scheduling to ancillaries (SIU), and clinical documents to repositories (MDM). Every hospital integration engine in production in AU, NZ, and the US today carries v2 traffic; most will continue to for the next 10+ years.
How it differs across Australia, New Zealand, and the United States
In Australia, HL7 v2 variants are widely used under state-level profile guidance, with ADHA and HL7 Australia providing national reference content. In New Zealand, HISO maintains messaging standards and HL7 NZ provides community-validated v2 profiles. In the United States, v2 underpins lab reporting to state public health (ELR), immunisation registry reporting (IIS), syndromic surveillance, and most EHR-to-EHR messaging outside of US Core FHIR flows.
Common misconceptions
v2 is not going away. It is being augmented by FHIR for new use cases, but the installed base is too large to rip out. v2 is not human-readable by accident — the delimiter structure is designed for machine parsing and compact transport. v2 compatibility at the standard level does not imply interoperability at the profile level — most production v2 integrations require per-interface mapping work.
Related terms
- HL7 FHIR
- Integration engine
- CDA
Last updated: 18 April 2026