Clonic movement is an extremely rare complication that occurs after neuroaxial blockade. We have experienced three patients showing intermittent clonic movement on both lower extremities following spinal anesthesia or subdural administration of intended epidural steroid injection.The first and the second patients, 13-year-old boy and 51-year-old man, experienced clonic movement following standard spinal anesthesia with hyperbaric tetracaine with epinephrine for operation on lower extremities. The third one, 24-year-old man, was an outpatient for the treatment of intractable radiculopathy, previously had an L4 laminectomy. His clonic movement may have resulted from the accidental subdural administration of an intended epidural injection of 0.5% lidocaine 6 ml containing triamcinolone 40 mg. Clonic movement has appeared as the occurrence of intermittent, short-timed (about 2~5 seconds), severe annoying, bilateral involuntary muscle contraction on lower extremities at the stage of recovery. It sustained for about 4~19 hours. The treatment was mainly sedation with sedatives and inhalation anesthetics, and partially muscle relaxants or anticholinesterase. They recovered without any sequelae.