diff --git a/addons/hr_contract/hr_contract.py b/addons/hr_contract/hr_contract.py
index 3ad44ef3065..c0c4fe5c8bb 100644
--- a/addons/hr_contract/hr_contract.py
+++ b/addons/hr_contract/hr_contract.py
@@ -114,6 +114,19 @@ class hr_contract(osv.osv):
         'date_start': lambda *a: time.strftime("%Y-%m-%d"),
     }
 
+    def _check_dates(self, cr, uid, ids, context=None):
+        for contract in self.read(cr, uid, ids, ['date_start', 'date_end'], context=context):
+             if contract['date_start'] and contract['date_end']:
+                 if contract['date_start'] > contract['date_end']:
+                     return False
+        return True
+
+    _constraints = [
+        (_check_dates, 'Error! contract start-date must be lower then contract end-date.', ['date_start', 'date_end'])
+    ]
+
+
+
 hr_contract()
 
 # vim:expandtab:smartindent:tabstop=4:softtabstop=4:shiftwidth=4: