diff --git a/input/fsh/endpoint.fsh b/input/fsh/endpoint.fsh
index eef99357..d6541f47 100644
--- a/input/fsh/endpoint.fsh
+++ b/input/fsh/endpoint.fsh
@@ -174,6 +174,7 @@ This managing organization relationship is potentially independent of if the org
 * period MS
 * period ^short = "Overall deployment lifetime for this endpoint."
 * period ^comment = "usually indicating when the endpoint was deployed, and may indicate when this endpoint will be decommissioned."
+* extension contains MCSDPurposeOfUse named purposeOfUse 0..*
 
 
 
diff --git a/input/fsh/organization.fsh b/input/fsh/organization.fsh
index c928edb3..a0cb0516 100644
--- a/input/fsh/organization.fsh
+++ b/input/fsh/organization.fsh
@@ -36,3 +36,4 @@ represented as child Organizations of a parent Organization.
 * partOf only Reference(MCSDOrganization)
   * ^short = "If the Organization belongs to a single hierarchy, the partOf element shall be used."
   * ^definition = "If the Organization belongs to a single hierarchy, the partOf element shall be used."
+* extension contains MCSDPurposeOfUse named purposeOfUse 0..*
diff --git a/input/fsh/purpose.fsh b/input/fsh/purpose.fsh
new file mode 100644
index 00000000..2e84ae1f
--- /dev/null
+++ b/input/fsh/purpose.fsh
@@ -0,0 +1,27 @@
+Extension: MCSDPurposeOfUse
+Id: IHE.mCSD.PurposeOfUse
+Title: "Purpose of Use Extension"
+Description: """
+Set a purpose of use for an mCSD Endpoint or mCSD Organization.
+"""
+* ^context[+].type = #element
+* ^context[=].expression = "MCSDOrganization"
+* ^context[+].type = #element
+* ^context[=].expression = "MCSDEndpoint"
+* value[x] only CodeableConcept
+* valueCodeableConcept from http://terminology.hl7.org/ValueSet/v3-PurposeOfUse (preferred)
+
+Instance: MCSDSearchPurposeOfUse
+InstanceOf: SearchParameter
+Title: "Search on the IHE defined extension for Purpose of Use"
+Usage: #definition
+* id = "IHE.mCSD.Search.PurposeOfUse"
+* url = "http://profiles.ihe.net/ITI/mCSD/SearchParameter/IHE.mCSD.Search.PurposeOfUse"
+* description = "This SearchParameter enables finding Endpoints or Organizatoins by the purpose of use code."
+* name = "ihe-mcsd-purpose-of-use"
+* status = #active
+* code = #ihe-mcsd-purpose-of-use
+* base[+] = #Organization
+* base[+] = #Endpoint
+* expression = "(extension('http://profiles.ihe.net/ITI/mCSD/SearchParameter/IHE.mCSD.Search.PurposeOfUse').value as CodeableConcept)"
+* type = #token