Simultaneous diaphyseal fractures of the radius and ulna, often referred to as both-bone forearm fractures, are frequently encountered by orthopaedic surgeons. Adults with this injury are typically treated with open reduction and internal fixation because of the propensity for malunion of the radius and ulna and the resulting loss of forearm rotation. Large case series support the use of plate and screw fixation for simple fractures. More complex fractures are managed according to strain theory, with the intention of controlling rather than eliminating motion at the fracture site. This can be achieved with flexible plate and screw constructs or intramedullary nails. In general, results of surgical fixation have been good, with only modest losses of forearm strength and rotation. Notable complications include nonunion, malunion, and refracture after device removal.