As Complex Regional Pain Syndrome (CRPS) is a new and rare illness, medical cause for it has not yet been clearly found out. Nevertheless, the patients continue to file lawsuits for damage compensation against wrongdoers or their insurers, claiming that the cause of the illness is certain actions of the wrongdoers. Moreover, the claim amount reaches to hundreds of millions of won through billions of won unlike other illnesses. Therefore, CRPS has become an important legal issue in the damage compensation lawsuit. Even though the wound is slight, the development and result may be serious in the case of CRPS. As a result, a sharp conflict arises even regarding medical diagnosis of CRPS in the lawsuit. And, even if the medical diagnosis of CRPS is admitted, severe debates occurs with regard to many issues, which include the causation between accident and CRPS in connection with establishment of damage compensation liability and scope of liability like anamnesis, determination standard of aftereffect disability, and scope of admitted aftereffect medical expense in connection with scope of damage compensation. In this study, I will review fundamental medical research on CRPS up to now and discuss principal legal issues in the damage compensation lawsuit focusing on lower court rulings.