A radial nerve palsy complicates 1.8 to 17% (mean 11%) diaphyseal humeral fractures (13.7% in our series of 156 humeral fractures and nonunions treated by external fixation – Tsiagadigui, 2000). In about 75%, it is a primary lesion, related to the fracture before any attempt at treatment. In 60%, the fracture, most commonly with an oblique fracture line, involves the middle third. In children, a supracondylar fracture may be complicated by radial nerve palsy. Most nerve lesions correspond to neurapraxia or axonotmesis, due to traction or compression associated with bone angular deformity. Unfrequently, the nerve is impaled or severed by bone fragments, or may be trapped within the fracture in case of a spiral oblique middle or distal third humeral fracture with lateral displacement of the distal fragment. Iatrogenic injury during internal fixation or entrapment within periosteal callus are occasionally observed. The classical indications for early radial nerve exploration include open fractures requiring surgical debridement, or fractures with vascular compromise, or when the osteosynthesis is done by a plate. In all other cases, we recommend to investigate the integrity of the radial nerve by echography. In the absence of discontinuity, spontaneous neurological recovery is likely to occur and is monitored clinically and by electromyography; prevention of joint contracture is done by physiotherapy and by a wrist splint, maintaining the joint in slight dorsiflexion. In case of persistent palsy, neurolysis is indicated several months after the initial injury, the precise delay depending on the level of the fracture. Palliative treatment by tendon transfers offers in cases of persistent palsy excellent functional results. Tendon transfers may be indicated early after the fracture, in case of an irreparable radial nerve lesion.