Osteopetrosis is a sclerosing bone dysplasia characterized by hard, brittle bone secondary to dysfunctional osteoclast resorption. The three main forms are malignant autosomal recessive, intermediate autosomal recessive, and benign autosomal recessive. These various clinical manifestations ultimately are caused by genetic mutations affecting acidification of Howship's lacuna. Common radiographic features include a generalized sclerosis, rugger jersey spine, and endobone formation. Medical problems include cranial nerve palsies and pancytopenia. Because cortical and cancellous bone thickness is increased, medullary canals and cranial nerve foramina are overgrown with bone. Patients typically present with such orthopaedic problems as frequent fractures, coxa vara, osteoarthritis, and osteomyelitis. Management with open reduction and internal fixation and with intramedullary fixation of fractures is difficult but possible. Reported results of total hip and total knee arthroplasties are excellent.