The objective of this chapter is to introduce the osteopetrosis. The term osteopetrosis means bone and ‘petros’ stone. Osteopetrosis is a group of rare, heritable disorders of the skeleton which includes increased bone density and X-ray. Osteopetrosis is caused by the failure of osteoclast development or function and mutations in at least 10 genes have been identified as causative in humans. Etiopathogenesis, clinical manifestations of osteopetrosis, diagnosis and radiological features of osteopetrosis, differential diagnosis, antenatal diagnosis, recent advances and treatment of osteopetrosis are also discussed in this chapter. Osteopetrosis is a trait that can be inherited in an autosomal dominant, autosomal recessive or X-linked manner. The diagnosis of osteopetrosis is mainly on clinical and radiological appearance of skeleton. Treatment of osteopetrosis is comprehensive which includes hematologists, orthopedic surgeons, ophthalmologists and ENT specialists.