PURPOSE: To evaluate the incidence, risk factors and prognosis of delirium in elderly patients with intertrochanteric fractures of femur. MATERIALS AND METHODS: 162 patients who underwent operation for intertrochanteric fracture of femur from July 2005 to January 2007 were reviewed retrospectively. Delirium was diagnosed by using Confusion Assessment Method (CAM). Medical records were reviewed for the information of the patients, Gross motor function classification of Palisano et al. was used for the evaluation of ambulatory status. Univariate analysis and multivariate analysis were done to find out the risk factors. RESULTS: 2 cases out of 162 (1.2%) met the criteria of delirium at admission, and 39 cases (24.1%) after surgery. Univariate analysis and multivariate analysis identified age, hematocrit, dementia, the duration of opiate use, and pulmonary complication as risk factors. Hospital stay was longer and postoperative ambulatory status was worse in the patients with delirium. CONCLUSION: Delirium is a frequent complication of intertrochanteric fractures of old age and associated with worse results. Cognitive function as well as physical status should be evaluated before and after surgery. Delirium needs more active prevention and treatment for better results.