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Check out the Postman sample collection to help you get started using the UMLS REST API.

API Terms of Service

Retrieving UMLS Concept Information

URIs | Query Parameters | Sample Output

URIs with /CUI support the following use cases:

Note that ‘current’ in the URI can always be used to search against the latest UMLS publication.
You may use any valid UMLS release back to 2008AA in your URI if you would like to search against a particular version of the UMLS.


The base URI is

Sample URI Description Returned JSON Object classType
/content/current/CUI/C0009044 Retrieves CUI Concept
/content/current/CUI/C0009044/atoms Retrieve atoms in a CUI Atom
/content/current/CUI/C0009044/definitions Retrieve CUI definitions Definition
/content/current/CUI/C0009044/relations Retrieve CUI relations ConceptRelation

Query Parameters

Parameter name Required? Y/N Description Valid Values Default value Usage Note
apiKey Y An API key is required for each call to the API. Visit your UTS profile to obtain your API key. n/a n/a n/a

Sample Output

The default for calls under /CUI/{CUI} is to return UMLS CUIs.

Sample output for…

    "pageSize": 25,
    "pageNumber": 1,
    "pageCount": 1,
    "result": {
        "classType": "Concept",
        "ui": "C0009044",
        "suppressible": false,
        "dateAdded": "09-30-1990",
        "majorRevisionDate": "08-18-2015",
        "status": "R",
        "semanticTypes": [
                "name": "Injury or Poisoning",
                "uri": ""
        "atomCount": 63,
        "attributeCount": 0,
        "cvMemberCount": 0,
        "atoms": "",
        "definitions": "NONE",
        "relations": "",
        "defaultPreferredAtom": "",
        "relationCount": 5,
        "name": "Closed fracture carpal bone"