Postoperative delirium(POD) is acute change in cognitive status characterized by fluctuating consciousness and inattention within 30 days after operation and is associated with high incidence of morbidity, complication rates and longer hospitalization. To determine the incidence of POD and perioperative risk factors and to be helpful to predict high risk patients and to prevent POD, univariate and multivariate statistical analysis of clinical data of 216 laryngectomized and 32 COMMANDO cases. 1) POD developed 12.5%(27/216) in cases of laryngectomy and 9.3%(3/23) in cases of COMMANDO, and 12.2%(27/220) in male and 10.7%(3/28) in female. 2) Univariate analysis of 24 perioperative factors showed that older age, hypertension, postoperative low O2 saturation, postoperative decreased hemoglobin level, alcohol abuse, premorbid psychiatric constitution and postoperative elevated leukocyte count were thought to be responsible for POD(p<0.05). 3) Multivariate analysis showed that older age, hypertension, postoperative low O2 saturation and postoperative decreased hemoglobin level were high risk factors of POD(p<0.05). 4) The POD developed mostly postoperative 3-4th day and lasted 5.1 days. 5) The frequency of postoperative complications in POD group was higher than non-POD group. In conclusion, intensive care should be focused on the patients who have high risk factors for developing POD and POD could be preventable and decreased by predicting these risk factors during pre and postoperative period.