Delirium is an acute disturbance of consciousness usually occurring in elderly patients and secondary to worsening somatic condition. Dementia is the main risk factor. Delirium may be a symptom of infection, electrolyte disturbances, changes in pharmacologic treatment, or as a response to pain or hypoxaemia. In patients with diagnosed neoplastic disease, it is more commonly caused by hypercalcaemia, primary and secondary neoplasms in the CNS, or treatment (glucocorticosteroids, chemotherapy, radiotherapy of the head and neck region). The main management strategy in delirium is the identification and treatment of its causes. Pharmacological interventions should be administered rarely and for as short a time as possible. Prevention plays a critical role and includes avoiding drugs contraindicated in elderly patients (e.g. anticholinergics) and polypharmacy, promoting proper circadian rhythm, avoiding immobilization, correcting sensory deficits (audio and visual impairment), and proper hydration.