HL7's new AMS is live!   We are working with Fonteva to resolve log in issues. My Account

Section 1e: Version 3 (V3)
Section 4: Rules and References

HL7 Implementation Guide: LOINC Document Ontology, Release 1


The purpose for this implementation guide is to define how the LOINC Document Ontology can be implemented within systems as a foundation for powerful archiving, data mining, and information exchange based upon document types.


The implementation guide should prepare implementations to provide two key capabilities:

  • The ability to search for specific document types using a common ontology of document names. The specific need for the ontology is to provide semantics for names of documents that are exchanged between health information technology (HIT) systems.
  • The ability to search for focused collections of documents that have many different document types, but share common attributes. This capability can be accomplished through the use of filters applied to the LOINC Document Ontology axis attributes.


HL7 Implementation Guide: LOINC Document Ontology, Release 1 may also go by the following names or acronyms:

"HL7 IG: LOINC Clinical Document Ontology, R1", LOINC Doc Ontology, LOINC Document Ontology, LOINC Clinical Document Ontology


  • Clinical and Public Health Laboratories
  • Quality Reporting Agencies
  •  Standards Development Organizations (SDOs)
  • Regulatory Agency
  • Payors
  • Military Healthcare Organizations
  • EHR, PHR Vendors
  • Health Care IT Vendors
  • Clinical Decision Support Systems Vendors
  • Lab Vendors
  • Medical Imaging Service Providers
  • Healthcare Institutions (hospitals, long term care, home care, mental health)


  • Promotes standardization of the classification schemas applied to medical record contents, fostering better infrastructure for interoperability across organizations
  • Establishes a common query framework using the LOINC Document Ontology axes for navigating medical record contents, fostering improved liquidity of medical record contents in cross-organizational searches when compared to traditional searches for explicit document type codes
  • Promotes granular classification of medical record contents without compromising usability of user search interfaces


  • U.S. Department of Defense (DoD)
  • U.S. Department of Veterans Affairs (VA)


Work on this effort began in 2000 as collaboration between the LOINC Committee and the HL7 Document Ontology Task Force (DOTF), and was supported by the US Veterans Health Administration. The background and initial development of the ontology was described by Frazier et al. By 2003, the first set of attribute values (concepts in the ontology) were agreed, fully-specified names and LOINC terms created, and then subsequently published as part of the LOINC standard. Since then, Regenstrief and the LOINC Committee have continued to serve as the overall steward of this content, facilitating its continued evolution with the help of many contributors. The official publication of LOINC Document Ontology is contained in the LOINC release files distributed by Regenstrief. This ontology is a conceptual and implementable structure for labeling and organizing documents. Consistent with the vision of a healthcare learning system, the need for a document ontology has become acute as health information exchange and interoperability requirements dictate an increased level of data liquidity. To support the need for increased information exchange, some level of classification is needed to identify all possible resources.


The DOD and VA wish to develop an implementation guide that will detail this ontology for developers, and will also include implementation guidance to facilitate queries and retrieval of documents and notes by clinicians and administrative or financial staff. The acute need for an ontology of this nature has become apparent with the challenges inherent to establishing interoperability between the DOD and VA medical systems.


HL7 Implementation Guide: LOINC Document Ontology, Release 1


HL7 Implementation Guide: LOINC Clinical Document Ontology, Release 1 Expiration Jun 2017

(Download) (2.00 MB)


  • Medical Records
  • Terminology


  • DSTU




Structured Documents


  • Clinical and Public Health Laboratories
  • Clinical Decision Support Systems Vendors
  • EHR, PHR Vendors
  • Health Care IT Vendors
  • Healthcare Institutions
  • Lab Vendors
  • Medical Imaging Service Providers
  • Payors
  • Quality Reporting Agencies
  • Regulatory Agency
  • Standards Development Organizations (SDOs)


  • V3


  • Retired


  • Universal