diff --git a/addons/product/product.py b/addons/product/product.py
index a443ebe6033..e6b4b4c6348 100644
--- a/addons/product/product.py
+++ b/addons/product/product.py
@@ -214,7 +214,7 @@ class product_category(osv.osv):
     _columns = {
         'name': fields.char('Name', size=64, required=True, translate=True, select=True),
         'complete_name': fields.function(_name_get_fnc, type="char", string='Name'),
-        'parent_id': fields.many2one('product.category','Parent Category', select=True),
+        'parent_id': fields.many2one('product.category','Parent Category', select=True, ondelete='cascade'),
         'child_id': fields.one2many('product.category', 'parent_id', string='Child Categories'),
         'sequence': fields.integer('Sequence', select=True, help="Gives the sequence order when displaying a list of product categories."),
         'type': fields.selection([('view','View'), ('normal','Normal')], 'Category Type'),