Cerebral venous sinus thrombosis (CVST) in pediatric patients is rare, but the incidence of this disease is much higher in neonates. It is one of the important causes of neonatal seizures, and also can cause long term neurologic deficits. So far, there has been only one retrospective study of 10 neonatal CVST patients reported in Korea. However, there are no reported cases of prenatally diagnosed patient. We report a patient prenatally diagnosed with CVST which might cause severe neurologic complication, as we experienced significant decrease in size and number of thrombi without anticoagulation therapy and relatively benign clinical progress from birth to 1-year-old age.