Osteopetrosis is a hereditary disorder that is caused by a bone resorption defect and characterized with diffuse sclerosis of the bones. The severe form is detected in infancy because of macrocephaly, hepatosplenomegaly, deafness, blindness, and severe anemia. In this article we reported a case diagnosed as malign osteopetrosis while investigating the causes of anemia and hepatosplenomegaly.