The article presents the clinical picture of delirium characterized with acute, fluctuating altered levels of consciousness, inattention and cognitive function disorders. The article is comprised the most popular assessment scales for detecting (CAM - Confusion Assessment Method) and monitoring the course of delirium (DRS-R-98: Delirium Rating Scale-Revised-98; DOM: Delirium-O-Meter). The scales mentioned above contain unequivocally defined rating criteria of the patient's clinical state. The article mentions scientific studies concerning predisposing and precipitating factors for delirium such as age, severity of illnesses, cognitive impairment, metabolic and electrolyte disturbances, grouped according to the recommendation grades based on scientific evidence and the opinion of experts. Categories of recommendation of possible therapeutic intervention are presented with special emphasis being put on interventions that are always beneficial, useful, successful and safe. Moreover, recommendable pharmacological treatment methods (haloperidol, new antipsychotic drugs) as well as non-pharmacological ones (comprising routine screening of cognitive functions, comprehensive medical and nursing care) are described.