• Agnogenic myeloid metaplasia is a chronic myeloproliferative disorder characterized by splenomegaly, leukoerythroblastosis, extramedullary hematopoiesis, teardrop-shaped red blood cells, and fibrosis of the bone marrow. It is a disease of adults, with only one case report in the pediatric literature. The symptoms of the patient in this case clearly fit the diagnostic criteria of this disease. Myelofibrosis in children is usually of the acute type, presenting in infancy and running a fulminant, fatal course with minimal or mild splenomegaly. Red blood cells are usually normal on morphologic examination.Three infants, including two siblings, presented at ages 9, 10, and 16 months with clinical and laboratory findings consistent with agnogenic myeloid metaplasia. The occurrence of the disease in these siblings is suggestive of an autosomal recessive mode of inheritance.