Olecranon apophyseal nonunion is an elbow injury from overuse that affects adolescent athletes such as baseball pitchers who participate in overhead throwing sports. However, such injury is rare in collision sports. Here, we report two patients with this condition who are Judo athletes. The purpose of this report was to describe three elbows with olecranon apophyseal nonunion in two adolescent patients participating in Judo. This is a case series; the level of evidence is 4. Two 15-year-old patients were evaluated. One suffered from unilateral and the other from bilateral chronic posterior elbow pain. They were diagnosed with olecranon apophyseal nonunion, which was treated using internal fixation and bone grafting. Radiographic evidence of the apophyseal union was observed four months postsurgery. Two elbows were treated with tension band wiring, then they underwent hardware removal six months postsurgery. Both patients returned to their previous levels of activities six months postsurgery. Internal fixation using autologous bone grafting was a useful treatment for these Judo athletes with olecranon apophyseal nonunion.