diff --git a/testing/node-driver/src/integration-test/kotlin/net/corda/testing/driver/DriverTests.kt b/testing/node-driver/src/integration-test/kotlin/net/corda/testing/driver/DriverTests.kt
index f9c0a14e1b..fa8f9f697b 100644
--- a/testing/node-driver/src/integration-test/kotlin/net/corda/testing/driver/DriverTests.kt
+++ b/testing/node-driver/src/integration-test/kotlin/net/corda/testing/driver/DriverTests.kt
@@ -140,16 +140,42 @@ class DriverTests {
         }
     }
 
+    /**
+     * The uniqueness of nodes by the DSL is checked using the node organisation name and, if specified,
+     * the organisation unit name.
+     * All other X500 components are ignored in this regard.
+     */
     @Test(timeout=300_000)
 	fun `driver rejects multiple nodes with the same organisation name`() {
         driver(DriverParameters(startNodesInProcess = true, notarySpecs = emptyList())) {
             newNode(CordaX500Name(commonName = "Notary", organisation = "R3CEV", locality = "New York", country = "US"))().getOrThrow()
             assertThatIllegalArgumentException().isThrownBy {
-                newNode(CordaX500Name(commonName = "Regulator", organisation = "R3CEV", locality = "New York", country = "US"))().getOrThrow()
+                newNode(CordaX500Name(commonName = "Regulator", organisation = "R3CEV", locality = "Newcastle", country = "GB"))().getOrThrow()
             }
         }
     }
 
+    @Test(timeout=300_000)
+    fun `driver allows multiple nodes with the same organisation name but different organisation unit name`() {
+        driver(DriverParameters(startNodesInProcess = true, notarySpecs = emptyList())) {
+            newNode(CordaX500Name(commonName = "Notary", organisation = "R3CEV", organisationUnit = "Eric", locality = "New York", country = "US", state = null))().getOrThrow()
+            assertThatCode {
+                newNode(CordaX500Name(commonName = "Regulator", organisation = "R3CEV", organisationUnit = "Ernie", locality = "Newcastle", country = "GB", state = null))().getOrThrow()
+            }.doesNotThrowAnyException()
+        }
+    }
+
+    @Test(timeout=300_000)
+    fun `driver rejects multiple nodes with the same organisation name and organisation unit name`() {
+        driver(DriverParameters(startNodesInProcess = true, notarySpecs = emptyList())) {
+            newNode(CordaX500Name(commonName = "Notary", organisation = "R3CEV", organisationUnit = "Eric", locality = "New York", country = "US", state = null))().getOrThrow()
+            assertThatIllegalArgumentException().isThrownBy {
+                newNode(CordaX500Name(commonName = "Regulator", organisation = "R3CEV", organisationUnit = "Eric", locality = "Newcastle", country = "GB", state = null))().getOrThrow()
+            }
+        }
+    }
+    /** **** **/
+
     @Test(timeout=300_000)
 	fun `driver allows reusing names of nodes that have been stopped`() {
         driver(DriverParameters(startNodesInProcess = true, notarySpecs = emptyList())) {
diff --git a/testing/node-driver/src/main/kotlin/net/corda/testing/node/internal/DriverDSLImpl.kt b/testing/node-driver/src/main/kotlin/net/corda/testing/node/internal/DriverDSLImpl.kt
index 2d7b467d83..366cf98a98 100644
--- a/testing/node-driver/src/main/kotlin/net/corda/testing/node/internal/DriverDSLImpl.kt
+++ b/testing/node-driver/src/main/kotlin/net/corda/testing/node/internal/DriverDSLImpl.kt
@@ -664,7 +664,11 @@ class DriverDSLImpl(
     }
 
     override fun baseDirectory(nodeName: CordaX500Name): Path {
-        val nodeDirectoryName = nodeName.organisation.filter { !it.isWhitespace() }
+        val nodeDirectoryName = if (nodeName.organisationUnit != null) {
+            "${nodeName.organisation}-${nodeName.organisationUnit}"
+        } else {
+            nodeName.organisation
+        }.filter { !it.isWhitespace() }
         return driverDirectory / nodeDirectoryName
     }
 
@@ -1142,11 +1146,16 @@ private class NetworkVisibilityController {
 
     fun register(name: CordaX500Name): VisibilityHandle {
         val handle = VisibilityHandle()
+        val handleName = if (name.organisationUnit != null) {
+            "${name.organisation}-${name.organisationUnit}"
+        } else {
+            name.organisation
+        }
         nodeVisibilityHandles.locked {
-            require(name.organisation !in keys) {
-                "Node with organisation name ${name.organisation} is already started or starting"
+            require(handleName !in keys) {
+                "Node with the organisation name (+ unit name) \"$handleName\" is already started or starting"
             }
-            put(name.organisation, handle)
+            put(handleName, handle)
         }
         return handle
     }