Delirium is a common complication in hospitalized patients, particularly the elderly and those with cognitive impairment. It has been associated with higher mortality, prolonged hospitalization, cognitive impairment, higher rates of institutionalization at discharge and higher costs for healthcare systems. Its pathophysiology is poorly understood, and more recently a predominantly inflammatory origin has been proposed, which could explain its pervasiveness and association with underlying conditions. Clinically, it is characterized by acute onset with fluctuating course, inattention, disorganized thinking and altered level of consciousness. Diagnostic approach is based on the systematic search for triggering factors as well as the manifestations of the syndrome. Symptomatic treatment is based neuroleptics as first line treatment, and lorazepam when the former cannot be used or there are special indications. There is evidence that the condition can be prevented by resorting to multi-component strategies