A child with familial hemophagocytic lymphohistiocytosis (HLH) underwent allogeneic bone marrow transplantation (BMT) at age 5 months. At that time he showed delayed psychomotor development, and computed tomography revealed diffuse calcification. After BMT, a gradual neurodevelopmental normalization was observed. The potential ability of BMT to reverse neurodevelopmental deterioration in HLH should be considered.