The human body may be exposed to ischaemia and other stressors during surgery. Inhalational anaesthetics provide protection against these damages or can reduce the harm. This is called preconditioning. There are differences in the protective effect according to the inhalational agent and the stressor. We will examine the protective effect of inhalational agents in patients scheduled for liver, vessel, eye or lung surgery. We use biochemical markers and postoperative morbidity data to evaluate the possible protective effect.