We replaced anesthesia of operations, which has done under local or general anesthesia, by MAC(monitored anesthesia care) with various patient's monitoring devices such as BIS(bispectral index). From April 2003 to March 2004, 48 cases of operations were done in MAC with supplemental equipments. Induction, maintenance of anesthesia was performed by propofol and midazolam. Pain control was done by fentanyl and ketamine. For monitoring the depth of anesthesia in real time, and BIS scale was checked and was maintained in 40-60. All anesthesias were done by the anesthesiologist that was communicated with operator for information between patient's status and operation procedures. All operations and anesthesias progressed with stability and safety, and there was no major postoperative complication. Because BIS was relatively accurate device, there was no over dose of anesthetic agents, which was induced by patient's uncertain pain complain under sedation and no anxiety of operator, that was raised by no responsive patient. BIS made possible that operation under MAC was effective and safe, operator perform it with non-stress condition and followed by good surgical result.