Nalbuphine is becoming a common analgesic used in hysteroscopic operations. The aim of this study was to identify the median effective dose (ED50) and 95% effective dose (ED95) of nalbuphine combined with propofol in painless hysteroscopy.Twenty-five patients aged 18-60 years with an American Society of Anesthesiologists classification of I-II who were scheduled for painless hysteroscopy were recruited. The initial dose of nalbuphine was set at 0.15 mg/kg and varied by 0.01 mg/kg according to the Dixon sequential method. The ED50/ED95 of nalbuphine combined with propofol for hysteroscopy was calculated by the probit method.The ED50 of nalbuphine was 0.122 (95% confidence interval (CI) 0.092-0.137) mg/kg, and the ED95 of nalbuphine was 0.153 (95% CI 0.138-0.361) mg/kg.The ED50/ED95 values of nalbuphine combined with propofol in painless hysteroscopy are 0.122 mg/kg and 0.153 mg/kg, respectively. Nalbuphine at 0.153 mg/kg combined with propofol is effective and safe for painless hysteroscopy.