Delirium is quite frequent in elderly patients who sustain hip fractures. The use of Meperidine by physicians, unaware of the possible emergence of delirium in elderly patients, is very popular. We have retrospectively examined the incidence of delirium in 181 consecutive patients admitted to the orthogeriatric ward with hip fractures. We used the confusion assessment method to establish the presence of delirium in all patients. A database search was conducted to identify which patients were treated by Meperidine, or Morphine, prior to delirium onset. We identified 92 cases, 44 of whom were treated by Meperidine alone, and the other 48 treated by Morphine alone. Delirium was diagnosed in 13 (27.1%) Morphine treated patients as compared with 19 (43.2%) treated by Meperidine (P<0.001). Age, cognitive status and opiate use were associated with perioperative delirium. A subset regression analysis showed that exposure to Meperidine was significantly associated with delirium (odds ratio 2.5, P<0.01), in contrast with Morphine. Our results confirm the association between exposure to Meperidine and delirium, suggesting that this drug should be withdrawn in elderly hip fractured patients undergoing surgery, and substituted by low dose Morphine analgesia. Reducing the incidence of delirium, by adopting such an approach, may result in a significant potential of savings in direct costs, related to treatment of delirium in this population.