What is HL7 FHIR?
HL7 FHIR is a key concept in healthcare IT that affects your practice operations and compliance. Qventive helps practices understand and implement HL7 FHIR with 30+ years of expertise.
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Plain-English explanation.
FHIR is a healthcare data exchange standard developed by HL7 International. It defines how clinical and administrative data should be structured, how systems should request and respond to data requests, and how authentication and authorization should work. FHIR uses modern web technologies (REST APIs, JSON, OAuth 2.0) that are familiar to developers outside healthcare.
Core concept: Resources. FHIR organizes healthcare data into discrete "resources" — Patient, Observation, Medication, Condition, Encounter, Practitioner, and about 150 others. Each resource is a defined data structure with standard fields. Applications exchange resources via REST APIs — making healthcare data exchange look architecturally similar to exchanging data between any modern web applications.
Why FHIR matters: it makes healthcare interoperability achievable without each integration being a custom project. App developers can build healthcare applications using familiar tools; EHR vendors can expose standard APIs rather than custom interfaces; patients can authorize apps to access their records using OAuth 2.0 patterns familiar from consumer technology.
How FHIR differs from the older standard.
HL7 v2 — the older HL7 messaging standard (v2.3, v2.5, v2.6 in common use) — uses pipe-delimited text messages transmitted via MLLP (Minimum Lower Layer Protocol) over TCP/IP. Widely deployed, still operational in most healthcare integration today, particularly for lab results and admission/discharge/transfer messages. Works well for its original purpose but requires specialized integration expertise.
FHIR — modern replacement using web-native patterns. JSON or XML data format, REST API (request/response over HTTP), OAuth 2.0 authentication. Familiar to any web developer. Better for patient-facing applications, mobile apps, and modern interoperability patterns.
Coexistence: FHIR and HL7 v2 coexist. FHIR is growing rapidly for new integrations; v2 continues to run existing integration infrastructure. Healthcare IT environments commonly have both. See our healthcare interoperability page for broader context.
Where FHIR is actually being used in 2026.
Patient-authorized app access
The most visible FHIR deployment. Patient apps (Apple Health, Google Fit, Fitbit, and specialized health apps) authenticate via OAuth 2.0 and pull patient records from certified EHRs using FHIR APIs. Driven by information blocking rule requirements and ONC certification. Every major EHR now exposes patient-facing FHIR API.
Provider-to-provider data exchange
Increasingly common. FHIR enables structured query for specific patient data between providers rather than bulk document exchange. Particularly useful for care coordination scenarios where specific data points matter (most recent lab values, current medications, allergies).
Payer data exchange
CMS Interoperability Rule (driven by 21st Century Cures Act) requires payers to expose patient data via FHIR APIs. Patient access API, Provider Directory API, and Payer-to-Payer data exchange all use FHIR. Medicare Advantage, Medicaid managed care, and CHIP plans subject to these requirements.
Clinical decision support
SMART on FHIR apps — clinical applications that run within EHRs using FHIR data access. Enables third-party clinical decision support tools to integrate with EHRs without custom integration projects. Growing deployment for specialty-specific decision support.
Bulk data export
FHIR Bulk Data Access (Flat FHIR) enables batch export of patient data sets for population health, research, and analytics. Asynchronous pattern designed for large data exports.
The version landscape.
FHIR R4 (Release 4) — normative version published in 2019. Currently the version ONC certification requires. Most production FHIR deployments are R4.
FHIR R5 (Release 5) — published in 2023, includes incremental improvements. Adoption emerging; not yet widely deployed in production healthcare integration.
US Core — US-specific implementation guide on top of FHIR R4. Defines data elements and constraints specific to U.S. healthcare use cases. ONC certification requires US Core compliance.
HL7 FHIR specification for authoritative documentation.
What Practices Ask About What is HL7 FHIR
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