OBJECTIVE: The primary purpose of this study was to assess risk factors for delirium in patients staying in a surgical ward for more than 5 days. The secondary purpose was to assess outcomes in patients with delirium. BACKGROUND: Delirium is a syndrome characterized by acute fluctuations in mental status. Patients with delirium are at increased risk of adverse inpatient events, higher mortality and morbidity rates, prolonged hospital stays, and increased health care costs. METHODS: Participants in this study were 2168 patients who had been admitted to the surgical ward of St. Luke's International Hospital for 5 days or more between January 2011 and December 2014. Data on these patients were collected retrospectively from hospital medical records. Firstly, univariate and multivariate analyses were conducted to identify risk factors for delirium. Secondly, morbidity and mortality associated with delirium were analyzed. RESULTS: Delirium occurred in 205 of 2168 patients (9.5%). Age, physical restraint, past history of a cerebrovascular disorder, malignancy, intensive care unit stay, pain, and high blood urea nitrogen value were significant risk factors for delirium in the multivariate analysis. Among these, age was the strongest factor, with an odds ratio for delirium of 12.953 in patients 75 years of age or older. The length of hospital stays and the mortality rates were higher in patients with delirium. CONCLUSIONS: Results showed that age, and also physical restraint, past history of cerebrovascular disorder, malignancy, intensive care unit stay, pain, and high serum blood urea nitrogen were important factors associated with delirium in patients hospitalized for more than 5 days in a surgical ward.