Eighty patients scheduled for a hip or knee replacement surgery were randomized to receive oral ramelteon (n=41) or placebo (n=39) for the prevention of post-operative delirium. The primary outcome of interest was the incidence of delirium during post-operative day 0 and post-operative day 1-2, as measured by the Aldrete score. Secondary outcomes included the Delirium Rating Scale Revised 98 (DRS-R-98) severity score with and without delirium, duration of delirium, incidence of hospital discharge at post-operative day 2, the Richards-Campbell Sleep Questionnaire (MCSQ), and the incidence of adverse events. Outcomes were assessed up to post-operative day 2. Results revealed no statistical differences in all outcomes, at all time-points, between the ramelteon and placebo groups (p>0.05 for all).