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UMLS User Feedback

We listened to your feedback and compiled highlights below from a variety of resources of user interactions including the UMLS Annual Report, 2020 Request for Information (RFI) about the UMLS, conferences, and customer service inquiries.

Please note, we ask all UMLS licensees to complete the Annual Report to meet the reporting requirement in the License Agreement for Use of the UMLS Metathesaurus. You may have requested a UMLS license for the use of the UMLS, SNOMED CT, RxNorm, the Value Set Authority Center (VSAC), or another terminology product or service provided by the National Library of Medicine. You may be using this information directly or indirectly via a vendor’s application, such as medical coding software or an electronic health record (EHR).

UMLS Users

UMLS Licensee Count 2010-2022

number of licensees from 2010 to 2022

There are more than 30,000 active UMLS users around the world in 132 countries as of January 2023.

map of licensees

Reach of the UMLS

On the 2021 Annual Report, if you answered you are the owner of a application, tool, or system that utilizes the UMLS, the following displays the range of users who used your tool:

Number of users who use your tool Application count
1-10 421
11-100 204
101-1,000 168
1,001-10,000 126
More than 10,000 77

Top four industries where UMLS users work

  1. Health Care provider
  2. Software Development
  3. Research
  4. Education

Improvements based on user feedback

UMLS Terminology Services Redesign
In 2020, we updated the look and feel of the UMLS Terminology Services (UTS) website and the UMLS Metathesaurus Browser. The new web interface has the following new features:

  • Browse code information from UMLS vocabularies
  • Search and browse hierarchies from UMLS vocabularies
  • Navigate broader and narrower UMLS concepts
  • Easily search for CUIs, AUIs, or codes
  • Find partial matches for any query
  • Updated look and feel

In 2022, we moved the UTS from local servers to the cloud in order to improve overall stability and reliability of the application.

UMLS API Authentication
We have simplified UMLS API authentication. You can now
request data by simply adding an API key to your data request.

New UTS API endpoint
We have made a new API endpoint available for automating downloads of RxNorm, SNOMED CT, and UMLS release files. Simply provide the URL and your API key.

Python scripts
Several python scripts were added. An example is of our Crosswalking Vocabularies Using CUIs script which will crosswalk from a set of codes in one UMLS source vocabulary to a set of codes in another UMLS source vocabulary as long as the codes share a UMLS Concept. Visit UTS Python scripts

UMLS Metathesaurus Precomputed Subsets
In past years, we have required the use of MetamorphoSys to install and customize the UMLS Metathesaurus. For the 2022AB release, we are providing two ready-to-use precomputed subsets of the UMLS Metathesaurus that require no installation or customization.

  • UMLS Metathesaurus Full Subset (complete Metathesaurus data without any customization)
  • UMLS Metathesaurus Level 0 Subset (Includes only level 0 source vocabularies. Level 0 vocabularies do not have any additional restrictions beyond the standard license terms)

UMLS Metathesaurus History Files
We heard from you that the process of having to pull historical data out of multiple releases is burdensome so we created three new files that contain historical data from the UMLS Metathesaurus. It was created in preparation of removing older sources.

  • Concept History (MRCONSO_HISTORY.txt) - This file contains all atoms, concepts, and codes that were dropped from the UMLS Metathesaurus MRCONSO.RRF starting with the 2004AA release.
  • Relation History (MRREL_HISTORY.txt) - This file contains all relations dropped from the UMLS Metathesaurus MRREL.RRF file starting with the 2004AA release.
  • Source Vocabulary History (MRSAB_HISTORY.txt) - This file includes a row for every version of every UMLS source vocabulary updated in the UMLS Metathesaurus MRSAB.RRF file starting with the 2004AA release.
These history files are available from the UMLS Download page

We developed these educational materials:

We heard your feedback that you wanted to see rare disease content, as a result we added a new source called Orphanet. NLM is excited to add Orphanet, a source of rare disease content, to the UMLS Metathesaurus. This addition is based in part on work done by SNOMED International and INSERM to produce a mapping between SNOMED CT and Orphanet. Orphanet will be updated biannually with each UMLS release.

Example of tools that use the UMLS

UMLS users have extended the functionality of the UMLS in a variety of ways by developing APIs, automation scripts, and natural language processing tools. You can find a list of these on the UMLS Community web page.

examples of ways users use the umls

Want to add your tool? Send a request to the NLM Help Desk ( with the subject line: "UMLS Community". Be sure to include a link to your source code so that other UMLS users can adapt your tool.

Uses of NLM Terminology products

The top three ways you used each NLM Terminology products are listed in the following tables:


  • Processing of texts to extract concepts, relationships or knowledge
  • Facilitate mapping between terminologies
  • Extract specific terminologies from the Metathesaurus (e.g., MedDRA, MeSH, SNOMED CT)


  • Analytics
  • Reference Value Sets
  • Information Exchange
VSAC and value sets

  • Report clinical quality measures (CQMs) to CMS
  • Access content through VSAC FHIR terminology service
  • Author value sets
NIH CDE Repository

  • Exploring or browsing
  • Seeking specific information (definitions, codes, mapping, etc.)
  • Reference, verification, or comparison to other data

Thank you for all your feedback, we have multiple places to stay up to date with the UMLS:

You can always submit feedback through the NLM customer support portal.

Last Reviewed: January 5, 2023