diff --git a/partner_multi_relation/models/res_partner_relation.py b/partner_multi_relation/models/res_partner_relation.py
index 0907ab202..37335715f 100644
--- a/partner_multi_relation/models/res_partner_relation.py
+++ b/partner_multi_relation/models/res_partner_relation.py
@@ -43,12 +43,22 @@ class ResPartnerRelation(models.Model):
 
     @api.model
     def create(self, vals):
-        """Override create to correct values, before being stored."""
+        """Override create to correct values, before being stored.
+        Check to make sure each unique relation stays unique"""
         context = self.env.context
         if 'left_partner_id' not in vals and context.get('active_id'):
             vals['left_partner_id'] = context.get('active_id')
+        if not self.check_is_unique(vals):
+            raise ValidationError(_('Relation already exists!'))
         return super(ResPartnerRelation, self).create(vals)
 
+    @api.model
+    def write(self, vals):
+        """Check to make sure each unique relation stays unique"""
+        if not self.check_is_unique(vals):
+            raise ValidationError(_('Relation already exists!'))
+        return super(ResPartnerRelation, self).write(vals)
+
     @api.constrains('date_start', 'date_end')
     def _check_dates(self):
         """End date should not be before start date, if not filled
@@ -154,3 +164,24 @@ class ResPartnerRelation(models.Model):
                     _('There is already a similar relation with '
                       'overlapping dates')
                 )
+
+    @api.multi
+    def check_is_unique(self, vals):
+        if 'type_id' in vals:
+            type_id = vals['type_id']
+        else:
+            type_id = self.type_id.id
+        type_rec = self.env['res.partner.relation.type'].\
+            search([('id', '=', type_id)])
+        if 'right_partner_id' in vals:
+            right = vals['right_partner_id']
+        else:
+            right = self.right_partner_id.id
+        res = self.search([('type_id', '=', type_id),
+                           ('right_partner_id', '=', right)])
+        if (type_rec.is_unique and len(res) > 0):
+            return False
+        for rec in res:
+            if rec.type_id.is_unique:
+                return False
+        return True
diff --git a/partner_multi_relation/models/res_partner_relation_type.py b/partner_multi_relation/models/res_partner_relation_type.py
index dbcfd2570..c7d59e182 100644
--- a/partner_multi_relation/models/res_partner_relation_type.py
+++ b/partner_multi_relation/models/res_partner_relation_type.py
@@ -73,6 +73,11 @@ class ResPartnerRelationType(models.Model):
              " that do not fit the new criteria.\n"
              "Specify how this situation should be handled.",
     )
+    is_unique = fields.Boolean(
+        string='Is Unique',
+        help="If a relation type is unique, then there cannot be 2"
+             "relations with the same parties and the same type.",
+    )
 
     @api.model
     def get_partner_types(self):
@@ -255,7 +260,6 @@ class ResPartnerRelationType(models.Model):
     def write(self, vals):
         """Handle existing relations if conditions change."""
         self.check_existing(vals)
-
         for rec in self:
             rec_vals = vals.copy()
             if rec_vals.get('is_symmetric', rec.is_symmetric):
diff --git a/partner_multi_relation/views/res_partner_relation_type.xml b/partner_multi_relation/views/res_partner_relation_type.xml
index b82e704b5..8af8a910f 100644
--- a/partner_multi_relation/views/res_partner_relation_type.xml
+++ b/partner_multi_relation/views/res_partner_relation_type.xml
@@ -11,6 +11,7 @@
                     <field name="contact_type_right" />
                     <field name="allow_self" />
                     <field name="is_symmetric" />
+                    <field name="is_unique" />
                 </tree>
             </field>
         </record>
@@ -47,6 +48,7 @@
                             <field name="allow_self" />
                             <field name="is_symmetric" />
                             <field name="handle_invalid_onchange" />
+                            <field name="is_unique" />
                         </group>
                     </sheet>
                 </form>