Clonic movement is a rare complication that occurs after neuraxial blockade. We report our experience with an 18-year-old man developing myoclonic movement on his both upper extremities following intrathecal injection of 0.5% hyperbaric bupivacaine for varicocelectomy. One and half hour after spinal anesthesia, he developed bilateral, rhythmic myoclonic movements on upper extremities. Two days after surgery, neck flexion was observed. Symptoms sustained for about one month but frequency and severity of clonic movement had been reduced by anticonvulsants and muscle relaxant therapy. Four weeks later, he recovered without any complication.