The purpose of the present study is to compare the injection pain of propofol with that of benzodiazepines when used for intravenous sedation. In addition, we evaluated the efficacy of coadministering a small dose of 1% lidocaine (20 mg) to reduce the pain accompanying propofol injection. Intravenous propofol, diazepam, midazolam, or flunitrazepam were administered on separate occasions to volunteers and outpatients. The degree of injection pain was evaluated by the Visual Analog Scale (VAS) ruler. The efficacy of premixed lidocaine with propofol was also compared among the patients. The venous pain of propofol was significantly more intense than that of the three other drugs (P < 0.05). The injection pain of diazepam was more intense than that of midazolam (P < 0.05). Many patients reported no pain when propofol was coadministered with lidocaine. The addition of a small dose (20 mg) of lidocaine reduced the VAS pain score to comparable levels observed for benzodiazepines. Because injection pain might affect the patients' comfort during sedation, the addition of lidocaine to the propofol injection is deemed useful for intravenous sedation.