What is known and objective Propofol is effective in sedation for upper gastrointestinal (UGI) endoscopy. However, the optimum dose is ill-defined. This study aimed to estimate the effective dose of propofol mono-sedation for successful endoscope insertion in healthy, non-obese Chinese adults undergoing single UGI endoscopy. Methods Twenty-six adult patients undergoing elective single UGI endoscopy were enrolled in this study. A modified Dixon's up-and-down method was utilized to assess the effective dose of propofol for successful endoscope insertion. The initial dose of propofol administered, 1.6 mg/kg, was adjusted with 0.1 mg/kg as a step size. The patient's responses to endoscope insertion were classified as either 'movement' or 'no movement'. When patient's responses were changed from 'movement' to 'no movement' or from 'no movement' to 'movement', a crossover was defined. After eight crossovers had been obtained, patient recruitment was stopped. The mean of midpoints of all crossovers obtained by the modified Dixon's up-and-down method in all 26 patients was defined as calculated median effective dose (ED50) of propofol for successful endoscope insertion. Furthermore, probit regression analysis was used to determine the dose of propofol where 50% (ED50) and 95% (ED95) of endoscope insertion attempts were successful. Results The calculated ED50 of propofol for successful endoscope insertion was 1.89 +/- 0.12 mg/kg. The probit regression analysis showed that ED50 and ED95 of propofol for successful endoscope insertion were 1.90 mg/kg (95% CI, 1.78-2.10 mg/kg) and 2.15 mg/kg (95% CI, 2.01-3.56 mg/kg), respectively. No any patient had hypoxaemia and gag reflex during the UGI endoscopy with propofol mono-sedation. What is new and conclusion In healthy, non-obese Chinese adults, propofol mono-sedation can provide excellent conditions of UGI endoscopy and the estimated ED50 of propofol for successful endoscope insertion is 1.89 +/- 0.12 mg/kg.