KeywordsNursing personnel · Delirium of mixed origin · Reliability · Validity Abstract Purpose: Postoperative delirium is the most well-known form of postoperative cognitive impairment in all patient groups, especially in the elderly. Delirium is a syndrome that causes serious consequences, increasing mortality and morbidity rates and extending the length of hospital stay. The aim of this study was to evaluate the validity and reliability of the Turkish version of the Nursing Delirium Screening Scale (Nu-DESC). Method: One hundred twelve patients who were hospitalized for a surgical operation in the orthopedics, neurosurgery, and general surgery clinic of a state hospital for 3 months were evaluated concurrently (and independently for delirium). Patients were observed by clinical nurses 3 times over a 24-h period. The presence of delirium was diagnosed by 2 neurologists according to DSM-IV criteria. Student's t test, the χ 2 test, and the Mann-Whitney U test were used, and construct validity, intrascale factor analysis, interrater reliability, and specificity and sensitivity (ROC) analyses were performed for descriptive analysis. SPSS 25.0 and MedCalc18.6 were used for statistical analysis. Results: Delirium was detected in 28 patients according to the Nu-DESC. The ICC (intraclass correlation) is 0.97 in the 95% confidence interval from 0.96 to 0.98 for agreement between nurses and neurologists for the total Nu-DESC score. Weighted κ rates were between 0.78 and 0.92. In the ROC analysis of the Nu-DESC scale, the optimum cutoff value calculated for the 1,344 observations and 112 patients was determined as > 1 according to the maximum sensitivity and the specific situation. Sensitivity at the cut-off point was 92.27; specificity was determined as 92.72. The Youden index was found to be J = 0.845 (0 < J = 0.845 < 1). Conclusion: We believe that Turkish translation of Nu-DESC is valid and reliable for clinicians, nurses, and researchers and will contribute to delirium studies. 41 Radtke FM, Franck M, Schneider M, Luetz A, Seeling M, Heinz A, et al. Comparison of three scores to screen for delirium in the recovery room. Br J Anaesth. 2008 Sep; 101(3): 338-43. 42 Radtke FM, Franck M, Schust S, Boehme L, Pascher A, Bail HJ, et al. A comparison of three scores to screen for delirium on the surgical ward. World J Surg. 2010 Mar; 34(3): 487-94. 43 Neufeld KJ, Leoutsakos JS, Sieber FE, Joshi D, Wanamaker BL, Rios-Robles J, et al. Evaluation of two delirium screening tools for detecting post-operative delirium in the elderly. Br J Anaesth. 2013 Oct; 111(4): 612-8. 44 Hargrave A, Bastiaens J, Bourgeois JA, Neuhaus J, Josephson SA, Chinn J, et al. Validation of a nurse-based delirium-screening tool for hospitalized patients. Psychosomatics. 2017 Nov -Dec; 58(6): 594-603.