Local anesthetics injected into the subarachnoid space always have the risk of total spinal anesthesia. In this report, the differential diagnosis and the involved mechanism have been discussed. A patient was planned to be operated under epidural anesthesia for surgical repair of an open tibial fracture. He lost consciousness 22 minutes after the additional drug injection (45 mg 0.25% bupivacaine and 0.1 mg fentanyl) for maintenance of the anesthesia. Use of fractional injections of small volumes into the epidural space is preferable to a large volume of bolus injections. Fractional injections are thought to prevent the build-up of a pressure gradient, which avoids the serious complications of central blockades.