Introduction: Delirium is a frequent complication in elderly patients after urgent abdominal surgery. Methods: Prospective study of consecutive patients aged >= 65 years who had undergone urgent abdominal surgery from 2017-2019. The following variables were recorded: age, sex, ASA, physiological state, cognitive impairment, frailty (FRAIL Scale), functional dependence (Barthel Scale), quality of life (Euroqol-5D-VAS), nutritional status (MNA-SF), preoperative diagnosis, type of surgery (BUPA Classification), approach and diagnosis of postoperative delirium (Confusion Assessment Method). Univariate and multivariate analyses were performed to analyze the correlation of these variables with delirium. Results: The study includes 446 patients with a median age of 78 years, 63.6% were ASA > III and 8% had prior cognitive impairment. 13.2% were frail and 5.4% of the patients had a severe or total degree of dependence. 13.6% developed delirium in the postoperative period. In the univariate analysis, all the variables were statistically significant except for sex, type of surgery (BUPA) and duration. In the multivariate analysis the associated factors were: age (P < .001; OR: 1,08; 95% CI: 1,038-1,139), ASA (P = .026; OR: 3.15; 95% CI: 1.149-8.668), physiological state (P < .001; OR: 5.8; 95% CI: 2.176-15.457), diagnosis (P = .006) and cognitive impairment (P < .001; OR: 5.8; 95% CI: 2.391-14.069). Conclusion: The factors associated with delirium are age, ASA, physiological state in the emergency room, preoperative diagnosis and prior cognitive impairment. (C) 2020 AEC. Published by Elsevier Espana, S.L.U. All rights reserved.