Delirium is a common problem with a reported incidence of 13%–61% in orthopaedic patients. The mortality rate for patients who develop delirium can be as high as 37%. Recent research indicates that delirium may not be completely reversible in all patients. The normal physiological changes of aging predispose elders to the development of delirium. Inadequate pain management and polypharmacy are major precipitating factors for the disorder. New models of delirium pathophysiology are focused on the effects of both direct brain insults and aberrant stress responses. This article will provide a brief overview of the clinical problem of delirium with a focus on the current research evidence regarding predisposing, precipitating, and organic factors that lead to delirium in elderly orthopaedic patients.