BACKGROUND:?In general, the dose requirement and complications of propofol are lower when used in the diluted form than in the undiluted form. The aim of this study was to determine the dose requirement and complications of diluted and undiluted propofol for deep sedation in endoscopic retrograde cholangiopancreatography. METHODS:?Eighty-six patients were randomly assigned to either group D (diluted propofol) or U (undiluted propofol). All patients were sedated with 0.02-0.03 mg/kg midazolam (total dose ≤2 mg for age