Abstract Background: Neglected Monteggia fracture dislocation in children constitutes significant disability in respect to pain, stiffness, deformity, neurological compromise and restriction of activities of daily living. Many treatment strategies have been described to manage neglected Monteggia fracture dislocation and one of these strategies is the ulnar osteotomy for restoration of the ulnar length and reduction of the radial head with annular ligament reconstruction for restoration of the elbow biomechanics for this difficult problem. Aim: Evaluation of the results of a new V-shaped corrective ulnar osteotomy without bone grafting with annular ligament reconstruction in management of neglected Monteggia fracture dislocation in children. Materials and methods: In a prospective study 16 patients with mean age of 7 years and 3 months, who presented with neglected Monteggia fracture dislocation, were studied. The time interval between injury and presentation ranged from 3 months to 20 months (mean 11.2 months). Eleven patients were classified as Bado type I, three as Bado type II and two as Bado type III. All children underwent open reduction of the radiocapitellar joint with V-shaped angulation-distraction osteotomy of ulna and annular ligament reconstruction. We used the Mayo elbow performance score for evaluation of our results. Results: The mean follow-up period was 19.5 months. All ulnar osteotomies healed uneventfully. The mean loss of pronation was 4°. Elbow flexion-extension range improved postoperative by 3° and no child complained of pain, deformity or restriction of activity. The elbow score was excellent in eight cases, good in five cases, and fair in three cases. Conclusion: V-shaped corrective ulnar osteotomy technique without bone grafting is a technically simple procedure, which achieves lengthening and angulation of the ulna simultaneously in the sagittal plane and reduces the radial head and with annular ligament reconstruction will suffices in most cases of missed monteggia fracture dislocation.