Two standards, two jobs
HL7 v2 is the long-standing message format hospitals use internally: pipe-delimited messages that announce events such as a patient admission (ADT), a lab result (ORU) or an order (ORM). It is compact, ubiquitous and supported by almost every lab and radiology system.
FHIR (Fast Healthcare Interoperability Resources) is a newer, web-style standard. Data is modelled as resources — Patient, Encounter, Observation — exchanged as JSON over REST APIs. It is easier for developers and suits mobile apps, portals and national exchanges such as ABDM.
A practical comparison
- ✓Best for inside the hospital: HL7 v2 — event messages between HIS, LIS, RIS and monitors.
- ✓Best for apps and external exchange: FHIR — APIs, portals, patient apps and ABDM record sharing.
- ✓Learning curve: FHIR is friendlier to web developers; HL7 v2 needs knowledge of segments, fields and local variations.
- ✓Variation: Both have local variations. Two HL7 v2 systems can disagree on field usage; FHIR reduces this with profiles.
Why most hospitals need both
Your lab analyser and older HIS likely speak HL7 v2 or proprietary formats. ABDM record sharing and modern apps need FHIR R4. The usual pattern is an integration layer that receives v2 events, normalises and validates them, and exposes FHIR APIs outwards. See how to approach an HL7 v2 to FHIR migration.
What this means for ABDM
ABDM exchanges health records as FHIR R4 bundles. You do not have to rebuild your internal systems around FHIR to take part; you do need a reliable way to produce valid FHIR from what you already store. Start with the resources listed in FHIR R4 resources for hospital integration, then follow the ABDM overview.
A simple decision rule
Keep HL7 v2 where it already works. Use FHIR at the edges: for ABDM, for new apps and for any API that outside developers will call. Avoid rewriting working interfaces just to change the format.
Frequently asked questions
Is HL7 v2 obsolete?
No. It remains the most widely deployed messaging standard inside hospitals and will coexist with FHIR for many years.
Is FHIR the same as HL7?
FHIR is a standard published by HL7 International. HL7 v2 and FHIR are different standards from the same organisation.
Which FHIR version should we use for ABDM?
ABDM uses FHIR R4. Confirm the exact profile versions in the current specifications.
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Talk to our team →This guide is general information for engineering and planning purposes. It is not legal advice, and regulations and specifications change; confirm current requirements with the relevant authority or qualified counsel.
