Delirium in older patients is a common problem, whether patients are seen in a community setting, in a hospital for medical or surgical intervention or in an intensive care unit. Evaluation of elderly patients with confusion is challenging and in delirium several aspects of cognition, including perception, mental data processing and memory, must be considered. Delirium is thought to result from imbalances in cholinergic, dopaminergic and other neurotransmitter systems. It may manifest as a hyperactive, a hypoactive or a mixed state that fluctuates over time and requires a low threshold for investigation and a high index of suspicion for diagnosis. Once the presence of delirium has been established management strategies include treating any precipitating events, modifying potential risk factors and reassuring and reorienting the patient. Accurate identification and management of delirium in the elderly is important because delirium is associated with cognitive impairment and with increases in both morbidity and mortality. This review will discuss the variable presentations of delirium in the elderly, a diagnostic approach to acute confusion in the elderly, the acute management of delirium and the prognostic implications of delirium in this population.