diff --git a/addons/website_event_questions/models/event_question.py b/addons/website_event_questions/models/event_question.py
index 4d058569d4c..195413c5929 100644
--- a/addons/website_event_questions/models/event_question.py
+++ b/addons/website_event_questions/models/event_question.py
@@ -40,6 +40,11 @@ class EventQuestion(models.Model):
                     raise UserError(_("You cannot change the question type of a question that already has answers!"))
         return super(EventQuestion, self).write(vals)
 
+    @api.ondelete(at_uninstall=False)
+    def _unlink_except_answered_question(self):
+        if self.env['event.registration.answer'].search_count([('question_id', 'in', self.ids)]):
+            raise UserError(_('You cannot delete a question that has already been answered by attendees.'))
+
     def action_view_question_answers(self):
         """ Allow analyzing the attendees answers to event questions in a convenient way:
         - A graph view showing counts of each suggestions for simple_choice questions
@@ -63,3 +68,8 @@ class EventQuestionAnswer(models.Model):
     name = fields.Char('Answer', required=True, translate=True)
     question_id = fields.Many2one('event.question', required=True, ondelete='cascade')
     sequence = fields.Integer(default=10)
+
+    @api.ondelete(at_uninstall=False)
+    def _unlink_except_selected_answer(self):
+        if self.env['event.registration.answer'].search_count([('value_answer_id', 'in', self.ids)]):
+            raise UserError(_('You cannot delete an answer that has already been selected by attendees.'))