Delirium is a complex syndrome defined as an acute, fluctuating syndrome of altered attention, awareness, and cognition. Delirium is common in the elderly, but unfortunately underdiagnosed. The consequences could be significant such as an increase in mortality, hospitalization, loss of autonomy, and increased risk to be institutionalized. The predisposing and precipitating factors are well known, but the pathogenesis is not yet identified clearly. However, evidence that delirium is a neurotoxic factor which develops due primarily to neurotransmitter (cholinergic insufficiency) and inflammatory (increase in stress response/neuroinflammation) mechanisms is increasing each passing day. Delirium is associated with serious complications, but can also be treatable if diagnosed early and managed properly. It is important to develop primary and secondary prevention and therefore close contact with the patient, ensuring adequate vision, hearing, nutrition, hydration, and sleep; informing the caregivers about delirium for recognizing early symptoms of delirium, mobilizing the patient as early as possible, and managing the pain are strongly recommended. Besides, clinicians must identify the real underlying medical conditions. If non-pharmacologic interventions are insufficient, pharmacologic therapy should be implemented.