Monteggia dislocation is a rare injury, but lead to serious functional consequences if it is not diagnosed and treated opportunely. It corresponds to a fracture of the ulna associated with radio-humeral dislocation. Bado classification is the most commonly used, which allows explaining the mechanism and guiding the treatment. In the acute stage, it is essential to make the diagnosis timely and reduce the ulna fracture, thereby achieving, in turn, the reduction of the radio-humeral joint. On occasions, the use of osteosynthesis is necessary to stabilize the ulna fracture. Those cases that are presented late are a challenge for the pediatric Orthopedic surgeon and require the use of reconstruction techniques, being the osteotomy of the ulna necessary in most cases.