Various methods are applied in the treatment of fresh and neglected Monteggia fractures. The purpose of this retrospective study was to evaluate the efficacy of various treatment methods, and assess the complexity associated with missed radial head dislocation. All fracture patients were reviewed between Jan 2012 and Dec 2016. A detailed comparison was made of the treatment methods between fresh Monteggia fractures and neglected Monteggia fractures with missed diagnosis of dislocation. A preliminary analysis of clinical information from 1081 patients in our center was investigated, and 42 were included in the final analysis. The fresh group included 25 patients with an average Mayo Elbow Performance Score of 96.3 +/- 2.7 and resulted in the following scores after treatment: 21 excellent, 3 good, and 1 fair. In the fresh group, 76% of patients received closed reduction. Treatment with a cast, elastic stable intramedullary nail, and the Kirschner wire stabilization with tension band wiring make up 80% of the choices for fixation treatment. No patients experienced associated vascular injuries, recurrent dislocation, or elbow dysfunction. The neglected group involved 17 patients with Mayo Elbow Performance Score of 92.1 +/- 9.3 and resulted in the following scores after treatment: 10 excellent, 4 good, and 3 fair. The locking compression plate (LCP) was the most common choice for postoperative immobilization in the neglected group (88.2%). Three patients in the neglected group experienced recurrent dislocation. This retrospective analysis indicates that the treatment of neglected Monteggia fractures is more complex than that of Monteggia fractures, and usually results in a worse recovery rate with a higher rate of recurrent dislocation and elbow dysfunction.