---
{
  "title": "FHIR Profiling: Extensions",
  "description": "In FHIR, you can define a profile not only for a resource but also for an extension.",
  "date": "2025-04-11",
  "author": "Ivan Bagrov",
  "reading-time": "3 min",
  "tags": [
    "FHIR Profiling",
    "FHIR Standard"
  ]
}
---
## FHIR Extensions in Profiles

In FHIR, you can define a [profile](https://www.health-samurai.io/articles/fhir-profiling) not only for a [resource](https://www.health-samurai.io/articles/extending-fhir-resources) but also for an extension. A profile on an extension allows for restricting the acceptable types of extension values, specifying a binding for a coded value, and describing the validation of the value using [FHIRPath](/articles/unlocking-fhirpath-power-a-deep-dive-into-static-type-analysis-for-robust-tooling).

Example of how to describe your own extension that describes a patient’s place of birth:


```javascript
POST /fhir/StructureDefinition

resourceType: StructureDefinition
id: my-extension
type: Extension
baseDefinition: http://hl7.org/fhir/StructureDefinition/Extension
url: http://example.org/fhir/StructureDefinition/my-extension
name: MyExtension
kind: complex-type
abstract: false
derivation: constraint
differential:
  element:
   - id: Extension.url
     path: Extension.url
     fixedUri: http://example.org/fhir/StructureDefinition/patient-birthPlace
   - id: Extension.value[x]
     path: Extension.value[x]
     min: 1
     type:
      - code: string
```

See also: [Extending FHIR Resources](/blog/extending-fhir-resources) and [FHIR Profiling](/blog/fhir-profiling).