PURPOSE: The purpose of this study was to report on the incidence and risk factors of perioperative delirium in elderly patients with hip fracture. MATERIALS AND METHODS: There were seventy four patients who were older than 65 years and who underwent an operation for hip fracture between April 2006 and February 2008. All the patients were tested with the Mini-Mental State Examination Korean version after admission and they were checked daily for the duration of their hospitalization. We diagnosed delirium by the Confused Assessment Method and we evaluated the risk factors for perioperative delirium. RESULTS: Delirium occurred in 21 patients (28.4%). The delirium group had a lower Mini-Mental State Examination Korean version score compared with that of the control group. The percentage of patients cared for in the intensive care unit (ICU) was significantly higher in the delirium group. There were statistically significant differences between the delirium group and the control group for the serum electrolytes, albumin and a past history of diabetes, stroke and CNS medications. CONCLUSION: Delirium is common in the elderly patients with hip fracture. Electrolyte disequilibrium and a low albumin level showed significant positive correlation between the delirium group and the control group. A history of stroke, diabetes and CNS medications are risk factors for delirium.