['The aim of this prospective study was to determine incidence, duration, and risk factors for postoperative delirium (PD) in elderly patients undergoing major abdominal surgery.', 'The incidence and risk factors of PD after major abdominal surgery in elderly patients are not well documented.', 'From May 2006 to May 2008, 118 patients aged 75 years or more without severe preoperative cognitive dysfunction (mini mental state examination score >10/30) and undergoing major elective abdominal surgery were included. The preoperative geriatric assessment battery consisted of 4 tests evaluating physical (instrumental activities of daily living and timed get up and go test score) and cognitive function (mini mental state examination score), and detecting the presence of an underlying depression (Short-GDS). After the operation, geriatric patients were assessed for PD by the Confusion Assessment Method. Univariate and multivariate analyses were used to determine risk factors for PD.', 'Overall, PD occurred in 28 patients (24%). Multivariate analysis showed that an American Society of Anesthesiologists status of 3-4 (P = 0.02), impaired mobility (timed get up and go test score >20 seconds) (P = 0.009) and postoperative tramadol administration (P = 0.0009) were risk factors for PD. The mortality rate was 14% in 28 patients with PD and 3.3% in 90 patients without PD (P = 0.051). The morbidity rate was 35.5% in 28 patients with PD and 32% in 90 patients without PD (NS). The mean hospital stay was 19 +/- 11 days for patients with PD and 14 +/- 8 for patients without PD (P = 0.01). Fifteen of 24 (62.5%) surviving patients with PD and 28 of 87 (32%) surviving patients without PD were discharged to geriatric rehabilitation unit (P = 0.007).'] Are impaired mobility , ASA status and administration of tramadol risk factors for postoperative delirium in patients aged 75 years or more after major abdominal surgery?