The cause of death in a 45-day-old male infant who was found apneic at home and died 21 hours later was disseminated intravascular coagulation (DIC). The patient was admitted to a hospital in a state of cardio-respiratory arrest. The initial diagnosis was interrupted sudden infant death syndrome. The patient remained apneic, and recurrent discharge of bloody stool was the dominant clinical findings. He died without spontaneous respiration being restored. The autopsy revealed hemorrhages in the lungs and the ventricular septum and the free wall of the left ventricle of the heart. Microscopically, fibrin thrombi were noted in the large intestine and heart. The DIC was probably triggered by a widespread endothelial injury caused by severe hypoxia and acidosis originating from the apnea and cardiac arrest lasting longer than 30 min.