Monteggia-(like)-lesions are a combination injury of the forearm characterised by a proximal ulnar fracture with concomitant dislocation of the radial head in the proximal radioulnar joint (PRUG). If there are also fractures of the radial head and/or the coronoid, these are referred to as Monteggia-like injuries. Monteggia(-like) injuries are serious lesions which, without adequate treatment, carry a high risk of permanent damage such as persistent movement restrictions, progressive osteoarthritis and pain. Adequate diagnosis and treatment are essential for a satisfactory postoperative outcome. CT imaging with 3D reconstruction is the gold standard for preoperative diagnosis and planning. Generally, anatomical reduction with osteosynthesis is the treatment of choice for Monteggia(-like) injuries. In the vast majority of cases, the surgical approach can be dorsal. Anatomical fixation of the ulnar fracture is crucial for surgical success and is usually achieved using (locking) plate osteosynthesis. Concomitant fractures of the radial head and/or coronoid as well as ligamentous injuries require special attention and should usually also be addressed.