BACKGROUND/AIMS: Propofol sedation is increasingly being used when performing upper gastrointestinal endoscopy because of its rapid onset and good recovery profile. For achieving safe sedation during endoscopy, close monitoring of the vital signs is necessary because of the sedation's potentially serious adverse effects. There are only a few studies on the induction of sedation with using propofol for endoscopy in Korea. The present study was undertaken to evaluate the adequate initial injected dose of propofol for achieving safe and effective sedation when performing upper gastrointestinal endoscopy in Koreans. METHODS: From March 2008 to July 2008, 150 subjects who visited Kwangju Christian Hospital were randomized into 3 groups. An initial bolus dose of 0.5 mg/kg, 1.0 mg/kg and 1.5 mg/kg of propofol was allocated to groups A, B and C, respectively. The effectiveness and safety profiles of each injected dose of propofol were prospectively assessed by measuring various parameters of the vital signs and the adverse events. RESULTS: Group C had a significantly shorter induction time and the patients in group C did not require additional injections of propofol without increasing adverse events, as compared to that of the other 2 groups. CONCLUSIONS: 1.5 mg/kg of propofol was found to be more appropriate than 0.5 mg/kg or 1.0 mg/kg of propofol as the initial injected dose for induction of sedation during performance of upper gastrointestinal endoscopy in Koreans.