We present a case of accidental injection of tranexamic acid instead of bupivacaine during spinal anesthesia. One minute after intrathecal injection of 3.5 mL of solution, the patient developed myoclonus of his lower extremities. Accidental intrathecal injection of the wrong drug was suspected and a used ampule of tranexamic acid discovered in the trash can. The ampules of tranexamic acid (500 mg/5 mL) and bupivacaine (5 mg/mL, Merck, Darmstadt, Germany) were similar in appearance. General anesthesia was induced. Ten hours later, the patient developed myoclonus of his upper extremities and face. His polymyoclonus was successfully treated with phenytoin, sodium thiopental infusion, sodium valproate and supportive care of the hemodynamic, and respiratory systems. The patient’s condition progressively improved to full recovery.