The aim of this study was to identify psychiatric and somatic risk factors associated with the development, severity and duration of postoperative delirium after vascular surgery. Forty-seven patients underwent aortic, carotid artery and peripheral artery surgery. Both, surgeon and psychiatrist, monitored patients preoperatively with daily follow up. Preoperative psychiatric assessment included standardized psychopathological scales for the detection of psychiatric symptoms and cognitive deficits. We diagnosed delirium using DSM IV criteria. Delirium Rating Scale was used to estimate delirium severity. Surgical parameters included patient history, diagnoses, medication and laboratory parameters. A statistical analysis was performed using multivariate regression analyses to find factors significantly associated with delirium development, severity, and duration. Thirty-six percent of the patients developed postoperative delirium after surgery. Comparison of different parameters revealed that especially preoperative depression symptoms and perioperative transfusions/infusions had significant predictive value for the development as well as for the severity of postoperative delirium.