Afibrinogenemia is a rare autosomal recessive disease. Its clinical manifestations vary in severity, ranging from minimal bleeding to cataclysmic hemorrhage, and can begin at birth or, sometimes, later. We report a case of a female infant, 10 months of age, hospitalized in the pediatrics department because of a postvaccination hematoma. Biologic exploration found congenital afibrinogenemia. Through this case, we review the clinical features of this disease and its management.