Patellofemoral pain syndrome, one of the most common knee problems, is diagnosed by excluding other diseases that can cause similar pain or symptoms. The authors have been wondered about why patellofemoral pain syndrome can cause severe pain even when there are no structural abnormalities in the knee. For these reasons, if there are no structural abnormalities in the knee itself, the authors have strongly suspected referred pain due to injury of the surround structures, especially quadriceps femoris. Therefore, the authors want to report the successful experience in reducing knee pain and improving symptoms by performing extra-corporeal shockwave treatment in a patient who is concurred with diagnosis of patellofemoral pain syndrome and is suspected of having myofascial pain syndrome or chronic muscle injury of quadriceps femoris.