452 elderly patients undergoing emergent surgical treatment of hip fracture were randomized to receive melatonin or placebo for a duration of five days after admission. The purpose of this trial was to determine the short-term effects of melatonin on the incidence, duration, and severity of delirium commonly seen in this patient population. Perioperative melatonin supplementation did not reduce the incidence of delirium, but was associated with a decrease in the proportion of patients with long-lasting episodes of delirium (>2 days) compared to placebo (14/55 vs. 23/49; p=0.02). All other secondary outcomes were similar between treatment groups.