Opioids has been reported to cause hyperalgesia. Opioid induced hyperalgesia (OIH) is defined as paradoxically lowering the threshold of pain after the exposure of opioid. Remifentanil is a short acting opioid that is commonly used during anesthesia and surgery. However, OIH was reported to occur after surgery when large amount of remifentanil was administered. On the other hand, nefopam is a centrally acting, non-opioid analgesic. Nefopam has been reported to have analgesic and anti-hyperalgesic effect.