Nalbuphine, a mixed agonist-antagonist type opioid, can precipitate abstinence syndrome in opioid-dependent patients especially in large doses. We can prevent this syndrome by avoiding the injection of agonist-antagonist type opioid to the patient who already has used opioid for a long time, and the method of relatively small dose increments in its use. We experienced a case of opioid withdrawal symptom in chronically morphine-administered patient via epidural catheter after using intramuscular nalbuphine for analgesia. The symptom was promptly relieved by intravascular morphine injection without any problems.