Aseptic humeral shaft nonunions are rare lesions, with less than 700 cases per year in France. This low frequency explains why they are difficult to manage. They can be hypertrophic or atrophic, with or without a defect. The diagnosis is made based on radiographs and/or CT scan images. Nonunion is suspected early on when a patient presents with abnormal motion at the fracture site 6 weeks after the initial injury event in the context of conservative treatment or has large residual displacement after initial treatment or an open fracture. The treatment for hypertrophic nonunion consists in applying stable, rigid fixation, most often using a large-fragment plate with 4.5 mm screws, combined with cancellous autograft. When combined with the osteoperiosteal decortication first described by Judet, it produces union in 98% of cases. Intramedullary (IM) nail fixation with an autograft is another possibility. In atrophic nonunions, resecting the ends and ensuring the soft tissues have good vitality will generally lead to fracture union. Nonunions with critical size defects (larger than 5 cm), which have a high risk of infection, are a treatment challenge that requires stable fixation and recourse to more complex treatments like the two-step induced membrane technique or vascularized fibular graft. In all cases, to avoid complex repeat revision, internal fixation with plate or IM nail must be combined with a bone graft in situ to maximize the chances of union.