Section 1a: Clinical Document Architecture (CDA®)
Section 2: Clinical and Administrative Domains

CDA® R2.1 (HL7 Clinical Document Architecture, Release 2.1)


The HL7 Version 3 Clinical Document Architecture (CDA®) is a document markup standard that specifies the structure and semantics of "clinical documents" for the purpose of exchange between healthcare providers and patients. It defines a clinical document as having the following six characteristics: 1) Persistence, 2) Stewardship, 3) Potential for authentication, 4) Context, 5) Wholeness and 6) Human readability.

A CDA can contain any type of clinical content -- typical CDA documents would be a Discharge Summary, Imaging Report, Admission & Physical, Pathology Report and more. The most popular use is for inter-enterprise information exchange, such as is envisioned for a US Health Information Exchange (HIE).



CDA® R2.1 (HL7 Clinical Document Architecture, Release 2.1) may also go by the following names or acronyms:

Clinical Document Architecture R2.1, CDA, CDA Release 2.1, CDA R2.1


  • Supports the exchange of clinical documents between those involved in the care of a patient
  • Supports the re-use of clinical data for public health reporting, quality monitoring, patient safety and clinical trials
  • Can be reused in multiple applications



None at this time, as the CDA R2.1 standard is a base V3 RIM standard which will be used by IG implementers.  Once those IG are created, the CDA R2.1 standard will be implemented.


Implementations for CDA R2 (previous version of CDA):

  • International users in countries where health information exchange (HIE) is well established such as Finland, Greece and Germany
  • Pilot HIEs in Canada, Japan, Korea, Mexico, Argentina and elsewhere
  • CDA is firmly in the plans for many of the nascent US HIEs and the US Military Health System
  • Columbia-Presbyterian in New York: Project on CDA note generation with knowledge management and controlled vocabulary
  • Queen Elizabeth II Hospital/Dalhousie University: CDA for decision support
  • Duke Clinical Research Institute: CDA as the Single Source Proof of Concept
  • The Mayo Clinic is the largest single producer of CDA documents, producing thousands of CDAs every week with the anticipation of reaching 50,000 notes per week



CDA® grew out of work that originated outside of HL7 in early 1996 when a group of physicians including Tom Lincoln, John Spinosa, Dan Essin, John Mattison and Bob Dolin began to meet to discuss the potential for structured markup in clinical documents. The earliest draft was called the Kona Architecture and was developed in 1997 after the group had joined HL7. Since that time, many people have worked on it and the basic ideas have been refined and developed along with the HL7 Version 3 framework and the Reference Information Model (RIM). The original group morphed into the HL7 Structured Documents Work Group which is responsible for CDA and other HL7 document types.

CDA introduces the concept of incremental semantic interoperability. What this means is that there is a range of complexity allowed within the specification and users must set their own level of compliance. The minimal CDA is a small number of XML-encoded metadata fields (such as provider name, document type, document identifier, and so on) and a body which can be any commonly-used MIME type such as pdf or .doc (Microsoft Word) or even a scanned image file.

While the body of such a document would not be interpretable for applications like decision support, the minimal, standard metadata set and display characteristics mean that such a document could be filed, searched, categorized and retrieved along with more richly-encoded documents. They would all be equally readable at the point of care.

The previous version of CDA is Release 2 which is used as the foundation for all current CDA Implementation Guides.

CDA R2.1 includes a number of enhancements to the base CDA standard:

 a. CDA R2 errata

  b. Extensions previously cited by CDA IGs

  c. Attributes omitted from the classes derived from the RIM

  d. Additional codes in value sets E.g. Mood codes

  e. The inclusion of tables within tables in the narrative

  f. Include current language about bindings.


Additional informative content on topics such as, the use of templates to constrain CDA and vocabulary binding syntax.



CDA® R2.1 (HL7 Clinical Document Architecture, Release 2.1)

(Download) (25.19 MB)


  • Cardiology
  • Care Provision
  • Clinical Genomics
  • Clinical Quality
  • Clinical Statement
  • Community-Based Health
  • Decision Support
  • Emergency Management
  • Laboratory
  • Medical Records
  • Patient Care
  • Patient Referral
  • Pharmacy
  • Public Health


  • Normative




Structured Documents


  • Implementation Guide


  • Clinical and Public Health Laboratories
  • EHR, PHR Vendors
  • Emergency Services Providers
  • Health Care IT Vendors
  • Healthcare Institutions
  • HIS Vendors
  • Lab Vendors
  • Local and State Departments of Health
  • Regulatory Agency


  • CDA


  • Active


  • Universal