MUP (medically unexplained pain) is a pain whose cause cannot be determined by diagnostic imaging, blood test, physical examination and past medical history, etc. Many departments have independently created the concept, definition, and diagnostic criterion in MUP. This leads to an abnormal situation in which each department has different disease concepts and diagnostic criteria. It is out-of-the-ordinary that physicians from the different departments make different diagnoses in the same patient. MUP has caused confusion in clinical practice. The medical community should make the unified disease concept, definition, and diagnostic criterion of MUP. For this purpose, the various scientific organizations involved in MUP need to discuss. In this case, the first priority should not be the majority vote, but the treatment outcomes. The solution to a medical controversy is to choose a medical theory or treatment method that produces better long-term results.