Case:A 6-year-old boy sustained complete radial nerve palsy with a Gartland type III supracondylar humerus fracture (SCHF). Posteromedial displacement of the distal fragment was so severe that the tip of the proximal fragment protruded subcutaneously at the anterolateral aspect of the antecubital fossa. Immediate surgical exploration was performed to reveal radial nerve laceration. Neurorrhaphy after fixation of the fracture resulted in full recovery of radial nerve function 1 year postoperatively.Conclusions:Severe posteromedial displacement with complete radial nerve palsy may warrant acute surgical exploration even in a closed SCHF because primary neurorrhaphy may achieve better results than late reconstruction.