Aim: We present details of a surgical technique to create an intramedullary canal to allow intramedullary fracture fixation in patients with osteopetrosis. Clinical cases are used to facilitate the description. Background: Osteopetrosis is a rare, hereditary condition characterised by hard, brittle, “marble bone;” primarily due to osteoclast dysfunction. Patients are prone to fractures and subsequently nonunions, periprosthetic fractures, and metal-ware failure are commonly seen. Due to the increased bone density, deformity, and obliteration of the medullary cavity, fracture fixation is also technically demanding. Technique: Creation of a medullary canal allows the use of intramedullary fixation rather than plate and screws for long-bone fractures. Key factors: • A new sharp drill bit should be used for each case as blunt drills are more likely to break. • Bone is drilled in a pulsatile fashion, with withdrawal every 2–4 seconds for bone swarf to be removed. • Constant cooling of the drill bit with saline to help prevent bone necrosis and drill breakage. • Regular exchanging of drill bit sizes to expand the canal. The smaller drills start the canal and are used to direct progress. Sequential expansion during canal creation is preferred. • Regular use of orthogonal radiographs to ensure correct canal positioning and prevent perforation. Conclusion: The creation of an intramedullary canal allows intramedullary fracture fixation. In our experience, this technique gives the orthopaedic surgeon a safe and effective method for treating long-bone fractures in patients with osteopetrosis. Clinical relevance: Fractures and nonunions in patients with osteopetrosis are difficult to manage; and by detailing this technique, a further option is now available for surgeons when deciding upon fixation method.