We describe a 5 1/2 year old boy who was diagnosed with mild autosomal recessive osteopetrosis based on the presence of bony sclerosis, extramedullary haematopoeisis, leukoerythroblastosis and visual impairment who had an allogeneic bone marrow transplant from a matched sibling donor. Conditioning regime was busulphan 16 mg/kg and cyclophosphamide 200 mg/kg. Apart from transient hypercalcaemia, there were no major post transplant complications. Four years post transplant, the extramedullary haematopoeisis has resolved completely with normal blood counts. Apart from a fracture after a trivial fall two months after transplant, he has not suffered any fracture related limb deformities.