A rare case of a fracture of the anatomical neck of the humerus associated with a posterior dislocation of the shoulder in a 43-year-old man is presented. It was managed by immediate surgery using locking plate osteosynthesis. The shoulder was immobilised for 5 weeks in a Gilchrist brace. The outcome was very good with a full range of motion and a stable shoulder at 1 year after injury, with no signs of avascular necrosis of the humeral head. The aetiology of this injury and possibilities of its treatment are discussed.