Most infants with hemophilia have no bleeding in the neonatal period even if birth trauma occurs. The explanation for this lack of bleeding in the first few days of life in most hemophiliacs is unknown. Maternal factors VIII and IX fail to cross the placenta and cannot, therefore, protect the neonate. There have, however, been an increasing number of reports of severe neonatal bleeding in hemophiliac neonates. Herein, a case of severe neonatal bleeding responsible for hypovolemic shock and disseminated intravascular coagulation masking the hemophilia and delaying its diagnosis is reported. Transfusion of twice the total globular mass and exchange-transfusion were required. Hemorrhagic gastric necrosis occurred, requiring subtotal gastrectomy. The diagnosis of severe hemophilia A (factor VIII = 1%) was established only at 17 days of age. At the age of five months, the child developed a dumping syndrome which improved under appropriate dietary therapy and finally resolved. Outcome was favorable and at the evaluation at two years of age the child was leading a normal life. This case underlines the difficulty of the diagnosis of hemophilia at birth. When there is no family history of bleeding, the diagnosis of hemophilia is usually missed in the neonatal period and established only later or retrospectively. Factors VIII and IX should consequently be measured in male neonates with unusual bleeding and an increased activated partial thromboplastin time, even if disseminated intravascular coagulation is present. Prompt diagnosis and initiation of specific therapy may lessen acute morbidity and prevent long-term sequelae in affected infants.