The prevalence of delirium following cardiac surgery in patients over 60 years has been reported in the range 30-52% (5, 6). Delirium is a condition characterized by consciousness disturbances, concentration disorders, memory disturbances and hallucinations. There have been associations made between the choice of sedative and the prevalence of delirium in ICU patients. In a multicenter randomized trial predominantly involving medical patients in the ICU, those assigned to receive dexmedetomidine had a reduced risk of delirium and spent less time undergoing mechanical ventilation7. It is not known if the choice of sedation agent in this population impacts on the incidence of delirium following cardiac surgery. Delirium is associated with increased morbidity, prolonged hospital stay, increased mortality8