{"head":{"title":"What Is HL7? Health Data Messaging Explained | OceanLab","description":"HL7 is the organisation behind major health data standards, and the name for its v2 messages that hospital systems still use. What it means for builds.","canonical":"https://oceanlab.in/glossary/hl7"},"crumbs":[{"name":"Home","path":"/"},{"name":"Glossary","path":"/glossary"},{"name":"HL7","path":"/glossary/hl7"}],"slug":"hl7","term":"HL7 (Health Level Seven)","aka":["HL7 v2","Health Level Seven"],"category":"Health software","short":"The standards body behind major health data standards, and the common name for its Version 2 messages that hospital systems use to exchange data.","body":[["HL7 stands for Health Level Seven. The organisation publishes several standards, including ",{"href":"/glossary/fhir","text":"FHIR"},". When engineers say HL7, they often mean HL7 Version 2: text messages split into segments and fields, sent between systems when something happens, such as a patient being admitted or a lab result being ready."],["HL7 v2 messages usually travel over an interface engine inside a hospital network rather than the public internet. Each site tends to use the standard a little differently, so every interface needs its own mapping."]],"why":["Much hospital data still moves as HL7 v2, so a clinical product often needs to receive or send it even when the vendor also offers FHIR. Interface work can be a large share of a health integration's cost and timeline."],"example":["A bed management tool needs to know when patients are admitted, moved or discharged. The hospital's interface team sends it a feed of admit, transfer and discharge messages from their interface engine, and the tool updates the ward board as each one arrives."],"inBuild":["We get sample messages from the site early, write the mapping per site, and keep every raw message so we can replay it. Incoming messages go through a queue and are handled ",{"href":"/glossary/idempotency","text":"idempotently"},", since interface engines resend on errors."],"mistakes":[["Assuming two hospitals send HL7 v2 the same way. Fields and codes differ by site."],["Not storing raw messages, so bugs cannot be traced or replayed."],["Starting interface work late. Hospital interface teams have long queues."]],"related":[{"href":"/glossary/fhir","label":"FHIR (Fast Healthcare Interoperability Resources)","detail":"A standard from HL7 for exchanging health data through modern web APIs, built from small, defined pieces called resources."},{"href":"/glossary/ehr","label":"EHR (electronic health record)","detail":"A digital record of a patient's health and care that is built to be shared with other providers, so it can follow the patient."},{"href":"/glossary/emr","label":"EMR (electronic medical record)","detail":"The digital version of a clinician's paper chart: a patient's medical and treatment history kept within one practice."},{"href":"/glossary/message-queue","label":"Message queue","detail":"A buffer that holds messages, such as tasks or events, until a worker is ready to process them, so the sender does not have to wait."},{"href":"/glossary/idempotency","label":"Idempotency","detail":"The property of an operation that has the same effect whether it runs once or several times, so it is safe to retry."}],"tools":[{"href":"/tools/ehr-integration-cost","label":"EHR integration cost","detail":"Free tool"},{"href":"/tools/patient-portal-cost","label":"Patient portal cost","detail":"Free tool"},{"href":"/tools/hipaa-checklist","label":"HIPAA checklist","detail":"Free tool"}],"links":[{"href":"/compliance/fhir-hl7","label":"FHIR and HL7 guide","detail":"Health data standards and how integrations use them."},{"href":"/software/healthdata","label":"Health data software","detail":"Health records, integrations and data platforms."},{"href":"/software/clinics","label":"Software for clinics","detail":"Clinic systems, the rules that apply and how they are built."}],"sources":[{"title":"HL7 FHIR specification (current published version)","url":"https://hl7.org/fhir/","checkedAt":"2026-10-25"}],"legal":false,"updatedAt":"2026-10-25"}