diff --git a/bika/lims/content/client.py b/bika/lims/content/client.py
index <HASH>..<HASH> 100644
--- a/bika/lims/content/client.py
+++ b/bika/lims/content/client.py
@@ -105,6 +105,13 @@ class Client(Organisation):
     def setTitle(self, value):
         return self.setName(value)
 
+    def getClientID(self):
+        ### If no ID is defined (old data) invent one
+        cid = self.getField('ClientID').get(self)
+        if cid:
+            return cid.decode('utf-8').encode('utf-8')
+        return self.getId().decode('utf-8').encode('utf-8')
+
     security.declarePublic('getContactsDisplayList')
     def getContactsDisplayList(self):
         wf = getToolByName(self, 'portal_workflow')
Retrieve ID as ClientID if database has no ClientID