Objectives: The aim of this study was to investigate the safety and efficacy of propofol sedation with a computer-assisted target-controlled infusionsystem in elderly patients during endoscopic retrograde cholangiopancreateography (ERCP). Methods: Included were 150 consecutive EPCP procedures elderly patients under propofol sedation with a TCI system. Patients were divided into 3 groups: group A, age 50-70 years (n=50); group B, age71-80 years (n=50); group C, age >80 years (n=50). We compared the propofol dose and adverse events (hypotension and hypoxemia) during ERCP. Results: Older patients required a lower target concentration of propofol with higher age period: Median target concentration are respectively 2.6 mu g/mL, 2.1 mu g/mL and 1.6 mu g/mL in the three groups. Hypotension tended to occur in the younger group, and hypoxemia occurred at a significantly higher rate in the older groups, although the number of cases was small. Low preoperative systolic blood pressure (<80 mm Hg) was associated with hypotension and abnormal pulmonary function was associated with hypoxemia in groups B and C. Conclusions: Elderly patients required lower doses of propofol with computer-assisted TCI system than younger patients. Attention to hypoxemia is necessary in elderly patients, particularly patients with abnormal pulmonary function.