Spinal block with intrathecal morphine is a popular anesthetic technique in cesarean delivery. This technique brings about good maternal and neonatal outcomes as well as provides good postoperative pain control. Systematic review showed intrathecal morphine produced long period of pain control up to 27 hours. However, some patients still experienced moderate to severe pain which defined as postoperative pain score >,= 4. From our institute survey, there were more than 50 percents of patients undergoing cesarean delivery receiving spinal block with intrathecal morphine experienced moderate to severe pain in the first 24 hours.