Postoperative cognitive impairment is a recognized clinical phenomenon. Previously, such clinical findings were called "adverse cerebral effects of anesthesia on old people". POCD is transient disturbance that can affect patients of any age but is more common in elderly people. Its relevance with the immediate post-operative phase was made clear. The aging of the population and new developments in medicine both lead to the increasing number of elderly patietnts undergoing extensive surgery. Mechanism of POCD is considered to be due to the inflammatory response and Ca2+ dysregulation of the brain. For the diagnosis of POCD, pscychometric tests are applied. Risk factors for POCD are aging, extensive invasive operations, intra and postoperative complications, and anesthetics. To reduce POCD, it is necessary to provide preoperative screening and cognitive training, minimally invasive surgery, the use of short-acting agents, meticulous anesthetic technique to prevent perioperative disturbances of homeostasis and organ ischemia, tight volume balance, and EEG monitoring.