HL7® message tooling implementation using Rust

A Cargo workspace: parse, navigate, validate, modify, and render Health Level Seven (HL7) messages in Rust. One crate per layer, one module per standard.

HL7®, and FHIR® are the registered trademarks of Health Level Seven International and their use of these trademarks does not constitute an endorsement by HL7.

This project uses the HL7® name in its package names, its organization name, and its domain, which is beyond fair use; we are requesting permission from HL7® for ways forward. The written-permission request was sent on 2026-08-25; the reply is pending.

This is organized by standard: one module per release family, so a "message", a "segment", or a "code" in one standard is never confused with the same word in another.

hl7                      this crate: re-exports one module per standard
  |
  +-- hl7::v2 = hl7-2    HL7 v2, releases 2.1-2.9 — parse, navigate,
  |                       validate, modify, and render, in three modes:
  |                       generic, schema-based, and struct-based
  +-- hl7::v3 = hl7-3    HL7 v3 — RIM backbone classes, coded values, the
                          three-level message envelope: a foundation, not
                          a full implementation

hl7::v2 and hl7::v3 are both here today. Room is left for hl7::fhir as that standard gets implemented, its own crate underneath, re-exported here the same way. Serde support is the same umbrella shape one layer up: serde-hl7 re-exports serde_hl7::v2 (the serde-hl7-v2 crate, for hl7-2's types) and serde_hl7::v3 (serde-hl7-v3, for hl7-3's), so neither hl7-2 nor hl7-3 depends on serde itself.

Install

cargo add hl7
cargo add hl7 --features derive   # pulls in hl7-2's derive macros

Depend on hl7-2 (or hl7-3) directly instead if you specifically want one standard with no umbrella indirection — this crate is nothing but thin re-exports (pub use hl7_2 as v2;, pub use hl7_3 as v3;) plus room for future standards.

Use

use hl7::v2;

let message = v2::parse("MSH|^~\\&|LAB||EPIC||20240101||ORU^R01|1|P|2.5\r\
                          PID|1||241900||SMITH^JOHN")?;
assert_eq!(message.get("PID-5.1")?.as_deref(), Some("SMITH"));

See hl7-2's README for the full tour of what hl7::v2 can do, and its spec/index.md for the normative specification.

See also

• hl7-2 — the HL7 v2 implementation this crate re-exports
• hl7-3 — the HL7 v3 foundation this crate re-exports as hl7::v3
• hl7-2-derive — the derive macros behind the derive feature
• serde-hl7 — Serde support, organized the same way: serde_hl7::v2 is serde-hl7-v2, serde_hl7::v3 is serde-hl7-v3
• hl7-2-mllp — MLLP: sending and receiving HL7 v2 messages over TCP
• hl7-2-from-er7-into-json, -into-xml, hl7-2-from-json-into-er7, hl7-2-from-xml-into-er7 — format conversions

License

MIT OR Apache-2.0 OR BSD-3-Clause OR GPL-2.0-only OR GPL-3.0-only