Although postoperative behavioral anomalies were first reported more than one hundred years ago, only in the past ten years has the profile for postoperative cognitive dysfunction (POCD) been defined. POCD is reversible and it has been suggested that the disorder has implications for increased mortality and morbidity if it is not diagnosed and treated early. At present the clinical presentation of POCD is thought to be variable and fluctuating, ranging from slight disorientation to coma. POCD can develop soon after surgery or appear several days later and its incidence is unknown as a result of the methodological difficulties involved in studying this entity. Of the various etiological factors that have been named, many can be modified during the period surrounding surgery. Once symptoms have developed,whether in the recovery unit or later, it is important to eliminate organic factors and begin treating the cause. The most important drugs for treatment are neuroleptics and benzodiazepines. We review the definition, epidemiology, etiology, pathophysiology and treatment of POCD and include a list of diseases and drugs associated with its development, as well as a description of psychological tests used for diagnosis.