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Health Level Seven (HL7), is a non-profit organization involved in the development of international healthcare informatics interoperability standards.[1] "HL7" also refers to some of the specific standards created by the organization (e.g., HL7 v2.x, v3.0, HL7 RIM).[2]

HL7 and its members provide a framework (and related standards) for the exchange, integration, sharing, and retrieval of electronic health information. The 2.x versions of the standards, which support clinical practice and the management, delivery, and evaluation of health services, are the most commonly used in the world.[3]

HL7 is an international community of healthcare subject matter experts and information scientists collaborating to create standards for the exchange, management and integration of electronic healthcare information.[4]

HL7 promotes the use of such informatics standards within and among healthcare organizations to increase the effectiveness and efficiency of healthcare information delivery for the benefit of all.[5]

The HL7 community is organized in the form of a global organization (Health Level Seven, Inc.) and country-specific affiliate organizations:

Health Level Seven, Inc. (HL7, Inc. ) is headquartered in Ann Arbor, Michigan.[6]


HL7 was founded in 1987 to produce a standard for hospital information systems. HL7, Inc. is a standards organization that was accredited in 1994 by the American National Standards Institute (ANSI).[7]

HL7 is one of several American National Standards Institute accredited Standards Developing Organizations (SDOs) operating in the healthcare arena. Most of these SDOs produce standards (sometimes called specifications or protocols) for a particular healthcare domain such as pharmacy, medical devices, imaging or insurance (claims processing) transactions. Health Level Seven’s domain is clinical and administrative data.

Today, HL7 has been adopted by several national SDOs outside the United States. Those SDOs are consequently not accredited by ANSI. However, HL7 is now adopted by ISO as a centre of gravity in international standardization and accredited as a partnering organization for mutual issuing of standards. The first mutually published standard is ISO/HL7 21731:2006 Health informatics—HL7 version 3—Reference information model—Release 1.

The name "Health Level-7" is a reference to the seventh layer of the ISO OSI Reference model also known as the application layer. The name indicates that HL7 focuses on application layer protocols for the health care domain, independent of lower layers. HL7 effectively considers all lower layers merely as tools.


HL7 and its members provide a framework (and related standards) for the exchange, integration, sharing, and retrieval of electronic health information. These standards define how information is packaged and communicated from one party to another, setting the language, structure and data types required for seamless integration between systems. HL7 standards support clinical practice and the management, delivery, and evaluation of health services, and are recognized as the most commonly used in the world.

HL7 standards are grouped into reference categories:

Section 1: Primary Standards - Primary standards are considered the most popular standards integral for system integrations, inter-operability and compliance. Our most frequently used and in-demand standards are in this category.

Section 2: Foundational Standards - Foundational standards define the fundamental tools and building blocks used to build the standards, and the technology infrastructure that implementers of HL7 standards must manage.

Section 3: Clinical and Administrative Domains - Messaging and document standards for clinical specialties and groups are found in this section. These standards are usually implemented once primary standards for the organization are in place.

Section 4: EHR Profiles - These standards provide functional models and profiles that enable the constructs for management of electronic health records.

Section 5: Implementation Guides - This section is for implementation guides and/or support documents created to be used in conjunction with an existing standard. All documents in this section serve as supplemental material for a parent standard.

Section 6: Rules and References - Technical specifications, programming structures and guidelines for software and standards development.

Section 7: Education & Awareness - Find HL7's Draft Standards for Trial Use (DSTUs) and current projects here, as well as helpful resources and tools to further supplement understanding and adoption of HL7 standards. All HL7 Standards can also be located by other classifications such as ANSI/ISO/HITSP approval and various search variables in our Master Grid.

HL7 encompasses the complete life cycle of a standards specification including the development, adoption, market recognition, utilization, and adherence. Please refer to our IP Policy for more information about how members and non-members can use the standards.[8]

The Reference Information Model (RIM) and the HL7 Development Framework (HDF) are the basis of the HL7 Version 3 standards development process. RIM is the representation of the HL7 clinical data (domains) and the life cycle of messages or groups of messages.[9] HDF is a project to specify the processes and methodology used by all the HL7 committees for project initiation, requirements analysis, standard design, implementation, standard approval process, etc.[10]

HL7 V3 vs. V2: A Comparison

HL7 version 2 message header

While the HL7 V2 standard specialists, the V3 standard was created mostly by clinical interface standard has been influenced strongly by work from volunteers representing the government and medical informatist users. This means that the level of formal modeling, complexity, and internal consistency is radically higher in V3 when compared to V2. Illustrated below (see Figure 3) is a sample of the difference in message formats between a V2 and V3 message.[11]

HL7 version 3 message header

The HL7 version 3 standard has the aim to support all healthcare workflows. Development of version 3 started around 1995, resulting in an initial standard publication in 2005. The v3 standard, as opposed to version 2, is based on a formal methodology (the HDF) and object-oriented principles.

The HL7 version 3 messaging standard defines a series of electronic messages (called interactions) to support all healthcare workflows. HL7 v3 messages are based on an XML encoding syntax.[12]


  1. "About Health Level Seven". Health Level Seven.
  2. "Healthcare Interoperability Glossary". Corepoint Health.
  3. Shaver, Dave. "The HL7 Evolution - Comparing HL7 Versions 2 and 3". Corepoint Health. Retrieved 16 February 2012.
  4. "Health Level Seven International". HL7.
  5. "Wikibook of Healthcare Informatics". Jorge Raúl Rodríguez Yañez. p. 125.
  6. "Contact Health Level Seven". Health Level Seven.
  7. ANSI
  8. HL7 International. "Introduction to HL7 Standards"
  9. HL7 Reference Information Model". HL7.
  10. HL7 International.FAQs.
  11. Corepoint Health. "HL7 Revolution: Versions 2 and 3 comparison.
  12. W3 Schools. XML Coding.