Background: Patellar dislocation is an orthopedic emergency and its reduction can be painful. The aim of this case is to show that the ultrasound-guided femoral nerve blockage can be effectively used in the pain management of patellar reduction in the emergency department (ED). Case Report: A 21-year-old man was admitted to our ED after suffering a fall down a flight of stairs. The initial physical examination and plain radiography showed a patellar dislocation in the right knee. We performed an ultrasound-guided femoral nerve blockage to provide a pain-free and comfortable patellar reduction. To our best knowledge, there is no manuscript except an old case series about use of the ultrasound-guided femoral nerve blockage in the management of patellar reduction in the medical literature. Procedural sedation is the preferred method used for this purpose in ED, but these medications need to be closely monitored because of their potential complications, such as nausea, vomiting, allergic reactions, and respiratory depression. Why Should an Emergency Physician Be Aware of This?: Ultrasound-guided femoral nerve blockage gave rapid and effective pain control without any complication during the reduction in this patient. Therefore, we suggest this technique be used for pain management during the reduction of a dislocated patella in the ED. (C) 2017 Elsevier Inc. All rights reserved.