diff --git a/erpnext/accounts/doctype/party_link/party_link.py b/erpnext/accounts/doctype/party_link/party_link.py
index e9f813c17c6..031a9fa4db0 100644
--- a/erpnext/accounts/doctype/party_link/party_link.py
+++ b/erpnext/accounts/doctype/party_link/party_link.py
@@ -2,7 +2,7 @@
 # For license information, please see license.txt
 
 import frappe
-from frappe import _
+from frappe import _, bold
 from frappe.model.document import Document
 
 
@@ -12,6 +12,17 @@ class PartyLink(Document):
 			frappe.throw(_("Allowed primary roles are 'Customer' and 'Supplier'. Please select one of these roles only."),
 				title=_("Invalid Primary Role"))
 
+		existing_party_link = frappe.get_all('Party Link', {
+			'primary_party': self.primary_party,
+			'secondary_party': self.secondary_party
+		}, pluck="primary_role")
+		if existing_party_link:
+			frappe.throw(_('{} {} is already linked with {} {}')
+				.format(
+					self.primary_role, bold(self.primary_party),
+					self.secondary_role, bold(self.secondary_party)
+				))
+
 		existing_party_link = frappe.get_all('Party Link', {
 			'primary_party': self.secondary_party
 		}, pluck="primary_role")