BACKGROUND: Surgical procedures carried out under local anesthesia are associated with patient discomfort and apprehension. The purpose of this study is to compare propofol and midazolam with regard to their suitability for the patient controlled sedation (PCS) technique during local anesthesia. METHODS: Forty unpremedicated, ASA physical status I day surgery patients undergoing elective minor surgery were randomly divided into two equal groups of patients who self-administered either propofol or midazolam intraoperatively. All patients initially received 0.5 g.kg-1 fentanyl. The bolus dose was either 20 mg (2 ml over 25 sec) of self-administered propofol or 0.5 mg (2 ml over 25 sec) of midazolam and lock-out period was 1 min. RESULTS: The onset of sedation following propofol was significantly faster than midazolam (p<0.05) and demands of propofol was significantly less than midazolam (p<0.05). There were no significant differences for postoperative recovery, sedation and comfort scale. CONCLUSIONS: Propofol was judged the more suitable agent for PCS than midazolam, because of its more rapid onset of sedation and less demands of drug.