diff --git a/docker/Transformation-Engine/src/main/kotlin/net/nhsd/fhir/converter/transformer/careconnect_transformers.kt b/docker/Transformation-Engine/src/main/kotlin/net/nhsd/fhir/converter/transformer/careconnect_transformers.kt
index e226638..eb5cec8 100644
--- a/docker/Transformation-Engine/src/main/kotlin/net/nhsd/fhir/converter/transformer/careconnect_transformers.kt
+++ b/docker/Transformation-Engine/src/main/kotlin/net/nhsd/fhir/converter/transformer/careconnect_transformers.kt
@@ -10,7 +10,9 @@ import org.hl7.fhir.r4.model.Coding as R4Coding
 import org.hl7.fhir.r4.model.DateTimeType as R4DateTimeType
 import org.hl7.fhir.r4.model.DomainResource as R4Resource
 import org.hl7.fhir.r4.model.Extension as R4Extension
+import org.hl7.fhir.r4.model.IdType as R4IdType
 import org.hl7.fhir.r4.model.MedicationRequest as R4MedicationRequest
+import org.hl7.fhir.r4.model.StringType as R4StringType
 import org.hl7.fhir.r4.model.UnsignedIntType as R4UnsignedIntType
 
 internal const val CARECONNECT_REPEAT_INFORMATION_URL =
@@ -40,6 +42,15 @@ internal const val UKCORE_PRESCRIBING_ORGANIZATION_URL =
     "https://fhir.hl7.org.uk/StructureDefinition/Extension-UKCore-MedicationPrescribingOrganization"
 
 
+internal const val CARECONNECT_DESCRIPTION_ID_URL =
+    "https://fhir.nhs.uk/STU3/StructureDefinition/Extension-coding-sctdescid"
+internal const val CARECONNECT_GPC_DESCRIPTION_ID_URL =
+    //TODO: what's the GPC url for this extension?
+    ""
+
+internal const val UKCORE_DESCRIPTION_ID_URL =
+    "https://fhir.hl7.org.uk/StructureDefinition/Extension-UKCore-CodingSCTDescId"
+
 internal val careconnectTransformers: HashMap<String, ExtensionTransformer> = hashMapOf(
     CARECONNECT_REPEAT_INFORMATION_URL to ::repeatInformation,
     CARECONNECT_GPC_REPEAT_INFORMATION_URL to ::repeatInformation,
@@ -48,7 +59,9 @@ internal val careconnectTransformers: HashMap<String, ExtensionTransformer> = ha
     CARECONNECT_LAST_ISSUE_DATE_URL to ::lastIssueDate,
 
     CARECONNECT_PRESCRIBING_AGENCY_URL to ::prescribingAgency,
-    CARECONNECT_GPC_PRESCRIBING_AGENCY_URL to ::prescribingAgency
+    CARECONNECT_GPC_PRESCRIBING_AGENCY_URL to ::prescribingAgency,
+
+    CARECONNECT_DESCRIPTION_ID_URL to ::descriptionId,
 )
 
 fun repeatInformation(src: R3Extension, tgt: R4Resource) {
@@ -131,3 +144,29 @@ fun prescribingAgency(src: R3Extension, tgt: R4Resource) {
 
     tgt.addExtension(ext)
 }
+
+fun descriptionId(src: R3Extension, tgt: R4Resource) {
+    val ext = R4Extension().apply {
+        url = UKCORE_DESCRIPTION_ID_URL
+
+        src.getExtensionsByUrl("descriptionId").firstOrNull()?.let {
+            val descIdExt = R4Extension().apply {
+                url = "descriptionId"
+                setValue(R4IdType(it.value.toString()))
+            }
+
+            addExtension(descIdExt)
+        }
+
+        src.getExtensionsByUrl("descriptionDisplay").firstOrNull()?.let {
+            val descDisplayExt = R4Extension().apply {
+                url = "descriptionDisplay"
+                setValue(R4StringType(it.value.toString()))
+            }
+
+            addExtension(descDisplayExt)
+        }
+    }
+
+    tgt.addExtension(ext)
+}
diff --git a/docker/Transformation-Engine/src/test/kotlin/net/nhsd/fhir/converter/transformer/prescription_id_test.kt b/docker/Transformation-Engine/src/test/kotlin/net/nhsd/fhir/converter/transformer/prescription_id_test.kt
new file mode 100644
index 0000000..e85128b
--- /dev/null
+++ b/docker/Transformation-Engine/src/test/kotlin/net/nhsd/fhir/converter/transformer/prescription_id_test.kt
@@ -0,0 +1,76 @@
+package net.nhsd.fhir.converter.transformer
+
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.params.ParameterizedTest
+import org.junit.jupiter.params.provider.ValueSource
+import org.hl7.fhir.dstu3.model.Extension as R3Extension
+import org.hl7.fhir.dstu3.model.IdType as R3IdType
+import org.hl7.fhir.dstu3.model.StringType as R3StringType
+import org.hl7.fhir.r4.model.MedicationStatement as R4MedicationStatement
+
+internal class PrescriptionIdTest {
+    @ParameterizedTest
+    @ValueSource(strings = [CARECONNECT_DESCRIPTION_ID_URL])
+    internal fun `it should create extension with the associated ukcore url`(extUrl: String) {
+        // Given
+        val r3Extension = R3Extension().apply {
+            url = extUrl
+        }
+
+        val r4Resource = org.hl7.fhir.r4.model.MedicationStatement()
+
+        // When
+        descriptionId(r3Extension, r4Resource)
+
+        // Then
+        val transformedExt = r4Resource.getExtensionByUrl(UKCORE_DESCRIPTION_ID_URL)
+        assertThat(transformedExt).isNotNull
+    }
+
+    @ParameterizedTest
+    @ValueSource(strings = [CARECONNECT_DESCRIPTION_ID_URL])
+    internal fun `it should carry over the descriptionId extension`(extUrl: String) {
+        // Given
+        val descId = 22298006L
+
+        val r3Extension = R3Extension().apply {
+            addExtension(R3Extension("descriptionId", R3IdType(descId)))
+        }
+
+        val r4Resource = R4MedicationStatement()
+
+        // When
+        descriptionId(r3Extension, r4Resource)
+
+        // Then
+        val transformedExt = r4Resource.getExtensionByUrl(UKCORE_DESCRIPTION_ID_URL)
+
+        assertThat(transformedExt.extension).hasSize(1)
+        val idType = transformedExt.extension[0].value
+        assertThat(idType.toString()).isEqualTo(descId.toString())
+    }
+
+    @ParameterizedTest
+    @ValueSource(strings = [CARECONNECT_DESCRIPTION_ID_URL])
+    internal fun `it should carry over the descriptionDisplay extension`(extUrl: String) {
+        // Given
+        val descDisplay = "description-display"
+
+        val r3Extension = R3Extension().apply {
+            addExtension(R3Extension("descriptionDisplay", R3StringType(descDisplay)))
+        }
+
+        val r4Resource = R4MedicationStatement()
+
+        // When
+        descriptionId(r3Extension, r4Resource)
+
+        // Then
+        val transformedExt = r4Resource.getExtensionByUrl(UKCORE_DESCRIPTION_ID_URL)
+
+        assertThat(transformedExt.extension).hasSize(1)
+        val actDescDisplay = transformedExt.extension[0].value
+        assertThat(actDescDisplay.toString()).isEqualTo(descDisplay)
+    }
+}
+