Fanconi anemia is a chromosomal instability syndrome associated with certain congenital abnormalities, defective hemopoiesis, and an increased risk of developing acute myeloid leukemia and some solid tumors. The diagnosis can be made at birth if congenital abnormalities are present but is often made in childhood when hematologic complications develop. The authors report a case of Fanconi anemia diagnosed in a child with no congenital abnormalities and normal bone marrow who first presented with a cerebellar medulloblastoma. The authors discuss diagnostic and therapeutic implications for such malignancies in Fanconi anemia.